Abstract The Cassini/Huygens mission is a collaborative mission of NASA and ESA to study the Saturnian system. Cassini Plasma Spectrometer (CAPS)is one of the scientific investigations onboard the Cassini orbiter. It consists of three separate spectrometers: Electron Spectrometer (ELS), Ion Mass Spectrometer (IMS) and Ion Beam Spectrometer (IBS). The University of Oulu has a co-investigator status in the CAPS project, and been mainly involved in simulating the structure and scientific performance of the IBS instrument. IBS is a high resolution hemispherical electrostatic analyser aimed to study the solar wind ions. This thesis contains an Introduction and five original papers. Papers I–III contain a detailed description of the simulation process of the IBS instrument and related results. In Paper I the manufacturing tolerances were calculated in order to verify that the high resolution requirements can be achieved using available manufacturing processes. In Paper II the simulations have been further developed and the instrument properties have been studied in more detail. In Paper III the simulation model is used to help the analysis and interpretation of the laboratory calibrations of the IBS flight model. Papers IV and V study the long-term fluctuations in solar wind and interplanetary magnetic field in the period range of 1–2 years (so called mid-term quasi periodicities, MTQP), using the wavelet transformation method to produce dynamic power spectra. In paper IV the MTQP structure in solar wind speed at 1 AU was studied using the longest available series of geomagnetic activity. It was shown that the long-term occurrence MTQP fluctuations roughly follows the long-term solar activity, suggesting that MTQP fluctuations are closely connected with the solar dynamo activity. Moreover, it was also noted that MTQP activity may offer a possibility for a precursory signal which could be used to predict significant changes in long-term solar activity. While Paper IV presents the temporally longest study of MTQP fluctuations, Paper V gives the spatially widest treatment of the same phenomenon. Paper V studies MTQP fluctuations in solar wind and interplanetary magnetic field measured by four probes in the outer heliosphere. It is shown that two MTQP fluctuations of different periods (1.3 and 1.7 years)co existed during solar cycle 22, while during solar cycle 21 only the 1.7-year band existed. This suggests that the solar dynamo acts differently during even and odd cycles. It is also shown that the two MTQP fluctuations during solar cycle 22 are organized latitudinally. While the 1.3-year periodicity originates from equatorial regions, the 1.7-year fluctuations arise at mid-latitudes. / Original papers Original papers are not included in the electronic version of the dissertation. Vilppola, J. H., Keisala, J. T., Tanskanen, P. J., & Huomo, H. (1993). Optimization of hemispherical electrostatic analyzer manufacturing with respect to resolution requirements. Review of Scientific Instruments, 64(8), 2190–2194. https://doi.org/10.1063/1.1143958 Vilppola, J. H., Tanskanen, P. J., Huomo, H., & Barraclough, B. L. (1996). Simulations of the response function of a plasma ion beam spectrometer for the Cassini mission to Saturn. Review of Scientific Instruments, 67(4), 1494–1501. https://doi.org/10.1063/1.1146881 Vilppola, J. H., Tanskanen, P. J., Barraclough, B. L., & McComas, D. J. (2001). Comparison between simulations and calibrations of a high resolution electrostatic analyzer. Review of Scientific Instruments, 72(9), 3662–3669. https://doi.org/10.1063/1.1392337 Mursula, K., Zieger, B., & Vilppola, J. H. (2003). Mid-term quasi-periodicities in geomagnetic activity during last 15 solar cycles: Connection to solar dynamo strength. Solar Physics, 212(1), 201–207. https://doi.org/10.1023/a:1022980029618 Mursula, K., & Vilppola, J. H. (2004). Fluctuations of the Solar Dynamo Observed in the Solar Wind and Interplanetary Magnetic Field at 1 AU and in the Outer Heliosphere. Solar Physics, 221(2), 337–349. https://doi.org/10.1023/b:sola.0000035053.17913.26

La récupération d'énergie mécanique de vibration à l’aide de transducteurs à capacité variable mène à l’étude de systèmes non linéaires complexes, mais présente des perspectives applicatives très prometteuses. Notre travail a porté sur l’étude d’une nouvelle famille de circuits d'interface pour transducteurs capacitifs. Entre autres avantages, ces circuits sont réalisables avec des rendements élevés à très basse puissance, typiquement dès quelques dizaines de nano-watts de puissance moyenne, ce qui les distingue des solutions présentées dans de l’état de l’art. De plus, Les circuits étudiés dans cette thèse ne contiennent aucun composant magnétique, ce qui constitue un atout considérable en termes de miniaturisation et d’intégration et permet eu outre la compatibilité avec l’imagerie par résonance magnétique. Les différentes structures qui constituent la famille de circuits proposés permettent de répondre à différentes contraintes imposées par le transducteur capacitif, en particulier le rapport des capacités maximale et minimale Cmax/Cmin. A partir d’une tension de sortie donnée, la tension appliquée sur le transducteur capacitif peut être modifiée en utilisant différents circuits ou en utilisant un circuit unique dont la topologie est modifiée à l’aide d’un interrupteur électronique. Les modèles théoriques développés prennent en compte le couplage électromécanique du transducteur de manière à décrire le comportement global des systèmes étudiés. Les circuits étudiés ont été validés expérimentalement avec deux transducteurs capacitifs de structure différente. En pratique, le rendement de ces circuits est proche de 80% pour des puissances converties aussi basses que la centaine de nano watts. / The mechanic vibration energy harvesting using variable capacitance transducers leads to the study of complex nonlinear systems but has very promising application perspectives. Our work focused on the study of a new family of interface circuits for capacitive transducers. Among all the advantages, these circuits are achievable with high efficiencies at very low power, typically a few tens of nanowatts average power, which distinguishes them from the solutions presented in the state of the art. Moreover, the circuits studied in this thesis do not contain any magnetic components, which is a considerable asset in terms of miniaturization and integration and also allows compatibility with magnetic resonance imaging. The various structures which constitute the family of circuits proposed make it possible to satisfy various constraints imposed by the capacitive transducer, in particular, the ratio of the maximum and minimum capacities Cmax / Cmin. For a given output voltage, the voltage applied to the capacitive transducer can be varied by using different circuits or by using a single circuit whose topology is modified by the operation of an electronic switch. In order to describe the overall behavior of the studied systems, the electromechanical coupling of the transducer is taken into account in the developed theoretical models. The studied circuits have been validated experimentally with two capacitive transducers of different structure. In practice, the output of these circuits is close to 80% for converted powers as low as the hundred nanowatts.

>Magister Scientiae - MSc / Human Immunodeficiency Virus (HIV), which is the cause of Acquired Immunodefiency Syndrome (AIDS) is a major global public health issue affecting over 37 million people worldwide and is responsible for claiming over 32 million lives since the discovery of the disease in 1981. Through effective diagnosis, treatment and prevention HIV is a manageable disease. Today, advanced antiretrovirals, known as HAART, serve as effective, first-line drug regimens, consisting of a variety of viral inhibitors, and have successfully helped viral suppression. However, issues arise with antiretrovirals due to patient non-adherence and the development of drug resistant mutations. Coupled with dormant HIV reservoirs, viral extinction is attenuated. It is therefore essential that effective alternative treatments are investigated. The exploration of nanomedicine for targeted drug delivery has shown an ability to prolong the drug circulation time, target drugs to specific sites in the body, and enhance drug effectiveness. A previous study demonstrated a novel therapeutic strategy that was based on a mutant version of the caspase-3 enzyme that can induce apoptosis in HIV infected cells. This therapeutic strategy has the potential to wipe out reservoirs of HIV infection. However, the therapeutic strategy lacked selectivity because the delivery mechanism was based on protein transduction technology which will result in the nonselective delivery of the drug. In this study, preliminary work towards the development of a targeted nanoparticle delivery system for this mutant caspase-3 enzyme is described. The study describes the synthesis of green fluorescent protein loaded alginate/chitosan nanoparticles that were functionalized with a DNA aptamer intended to target the nanoparticles to CD4 expressing cells, that are also targeted by HIV. The THP-1 cell line was used due to the ability of the cells to express CD4 receptors on the cell surface. The nanoparticles were synthesized through ionotropic gelation. The size, polydispersity, zeta potential and morphology were investigated by Dynamic Light Scattering and Scanning Electron Microscopy, respectively. The strongly negative zeta potential studies revealed stability of the nanoparticles in suspension and Scanning Electron Microscopy results showed an indicative collapse of the polymer network for the empty nanoparticles (i.e. nanoparticles not loaded with GFP), whereas solid, cuboid nanoparticles were shown for the GFP-loaded nanoparticles. Image-based fluorescence cytometry demonstrated that the GFP-loaded nanoparticles bind to the THP-1 cells that express the CD4 receptor. The results obtained are indicative of a potential drug delivery system for HIV treatment however, adjustments would need to be made to the current study to further develop this nanocarrier.

In diesem Report wird eine Niederenergie-Implantationskammer (NEI-Kammer) beschrieben, die im Forschungszentrum Rossendorf entwickelt und aufgebaut wurde. Die Kammer ermöglicht es, die Implantation von Ionen bei niedrigen Energien (< 30 keV) mit einer Implantationsanlage für mittlere Energien durchzuführen. In der Kammer werden der Ionenstrahl, den der Implanter liefert, auf die erwünschte niedrige Energie abgebremst. Dazu wird ein elektrostatisches Bremslinsensystem eingesetzt, das auf einem neuartigen Prinzip basiert. Das System besteht aus einer Sammellinse und einer Zerstreuungslinse, wobei die Öffnungsfehler beider Linsen entgegengesetzte Vorzeichen besitzen und sich gegenseitig kompensieren. Dadurch ist es möglich, Wafer gebräuchlicher Größe bei geringer Energie mit hoher Dosishomogenität zu implantieren. Die NEI-Kammer ist insbesondere für Forschungseinrichtungen eine vorteilhafte Lösung, da sie eine wesentlich kostengünstigere und flexiblere Alternative zur Anschaffung einer Niederenergie-Implantationsanlage darstellt.

Toll-like receptors (TLRs) are important pattern recognition receptors in the innate immune system of fish. Although ten years have passed since the first identification, the systematic knowledge about fish-specific TLR19 is still far insufficient. In present study, a phylogenetic analysis showed that TLR19 belonged to family 11, and clustered with TLR20 and TLR11/12 on the evolutionary tree. TLR20 is the closest paralogue of TLR19. The ectodomain of TLR19 contains 24 leucine-rich repeat (LRR) modules. The electrostatic surface potential analysis indicated that the modeled structure of TLR19 ectodomain showed much stronger polarity on the ascending lateral surface than on the descending lateral surface. The ascending lateral surface with strong electrostatic surface potential possibly mainly participates in the ligand binding of TLR19 ectodomain. The quite small dN/dS value at the TLR19 locus showed that TLR19 was very conserved. Approximately one third codons in the coding sequence of TLR19 were subjected to significantly negative selection, whereas only 5 codons underwent significantly positive selection. Overall, these findings possibly help in deepening the understanding to fish-specific TLR19.

This article presents the derivation of the thermodynamic expressions for the activation free energy and reaction rate constant for cosolvent reaction systems. These expressions account for the factors that are specific to solution-phase reactions, which include isotropic electrostatic effects and close-range solvent−solute interactions. This article discusses the idea that electrostatic effects can be correlated with the isotropic relative permittivity, and solvent−solute interactions can be correlated with the cosolvent mole fraction. This article also shows that this type of thermodynamic analysis is necessary for understanding certain nuances of solution-phase reaction processes not tractable by other types of analyses.

The Electrostatic Self-Assembly (ESA) technique possesses great advantages over traditional thin film fabrication methods, making it an excellent choice for a number of applications in the fields of linear and nonlinear optics, electronics, sensing and surface coatings. The feasibility of fabricating linear optical interference filters by ESA methods is demonstrated in this thesis work. Basic single-anion/single-cation ESA films are synthesized and their optical parameters -- refractive index and average thickness for individual bilayer -- are investigated to provide a basis for the in-depth design of optical filters. High performance dielectric stack filters and narrowband and wideband antireflection coatings are designed using TFCalc simulation software and are fabricated by ESA. Both bulk film sensitivity and layer sensitivity to manufacturing errors are provided. The significant agreement between simulation and experiment demonstrates the strong capability of ESA to precisely control the refractive index and produce excellent thin film filters. The performance of optical thin film filters is largely enhanced compared to the results of previous methods. The experiment results indicate that the ESA process may be used to fabricate optical filters and other optical structures that require precise index profile control. / Master of Science

L’intégration de plusieurs capteurs inertiels au sein d’un même dispositif de type MEMS afin de pouvoir estimer plusieurs degrés de liberté devient un enjeu important pour le marché de l’électronique grand public à cause de l’augmentation et de la popularité croissante des applications embarquées. Aujourd’hui, les efforts d'intégration se concentrent autour de la réduction de la taille, du coût et de la puissance consommée. Dans ce contexte, la co-intégration d’un accéléromètre trois-axes avec un gyromètre trois-axes est cohérente avec la quête conjointe de ces trois objectifs. Toutefois, cette co-intégration doit s’opérer dans une même cavité basse pression afin de préserver un facteur de qualité élevé nécessaire au bon fonctionnement du gyromètre. Dans cette optique, un nouveau système de contrôle, qui utilise le principe de l’amortissement électrostatique, a été conçu pour permettre l’utilisation d’un accéléromètre sous amorti naturellement. Le principe utilisé pour contrôler l’accéléromètre est d’appliquer dans la contre-réaction une force électrostatique générée à partir de l’estimation de la vitesse du MEMS. Cette technique permet d’augmenter le facteur d’amortissement et de diminuer le temps d’établissement de l’accéléromètre. L’architecture proposée met en oeuvre une méthode novatrice pour détecter et contrôler le mouvement d’un accéléromètre capacitif en technologie MEMS selon trois degrés de liberté : x, y et z. L'accélération externe appliquée au capteur peut être lue en utilisant la variation de capacité qui apparaît lorsque la masse se déplace. Lors de la phase de mesure, quand une tension est appliquée sur les électrodes du MEMS, une variation de charge est appliquée à l’entrée de l’amplificateur de charge (Charge-to-Voltage : C2V). La particularité de cette architecture est que le C2V est partagé entre les trois axes, ce qui permet une réduction de surface et de puissance consommée. Cependant, étant donné que le circuit ainsi que l’électrode mobile (commune aux trois axes du MEMS) sont partagés, on ne peut mesurer qu’un seul axe à lafois. Ainsi, pendant la phase d'amortissement, une tension de commande, calculée pendant les phases de mesure précédentes, est appliquée sur les électrodes d'excitation du MEMS. Cette tension de commande représente la différence entre deux échantillons successifs de la tension de sortie du C2V et elle est mémorisée et appliquée trois fois sur les électrodes d’excitation pendantla même période d’échantillonnage. Afin d’étudier la faisabilité de cette technique, des modèles mathématiques, Matlab-Simulink et VerilogA ont été développés. Le principe de fonctionnement basé sur l’amortissement électrostatique simultané a été validé grâce à ces modèles. Deux approches consécutives ont été considérées pour valider expérimentalement cette nouvelle technique : dans un premier temps l’implémentation du circuit en éléments discrets associé à un accéléromètre sous vide est présentée. En perspective, un accéléromètre sera intégré dans la même cavité qu’un gyromètre, les capteurs étant instrumentés à l’aide de circuits CMOS intégrés. Dans cette cadre, la conception en technologie CMOS 0.18μm de l’interface analogique d’amortissement est présentée et validée par simulation dans le manuscrit. / Recently, consumer electronics industry has known a spectacular growth that would have not been possible without pushing the integration barrier further and further. Micro Electro Mechanical Systems (MEMS) inertial sensors (e.g. accelerometers, gyroscopes) provide high performance, low power, low die cost solutions and are, nowadays, embedded in most consumer applications. In addition, the sensors fusion has become a new trend and combo sensors are gaining growing popularity since the co-integration of a three-axis MEMS accelerometer and a three-axis MEMS gyroscope provides complete navigation information. The resulting device is an Inertial measurement unit (IMU) able to sense multiple Degrees of Freedom (DoF). Nevertheless, the performances of the accelerometers and the gyroscopes are conditioned by the MEMS cavity pressure: the accelerometer is usually a damped system functioning under an atmospheric pressure while the gyroscope is a highly resonant system. Thus, to conceive a combo sensor, aunique low cavity pressure is required. The integration of both transducers within the same low pressure cavity necessitates a method to control and reduce the ringing phenomena by increasing the damping factor of the MEMS accelerometer. Consequently, the aim of the thesis is the design of an analog front-end interface able to sense and control an underdamped three-axis MEMSaccelerometer. This work proposes a novel closed-loop accelerometer interface achieving low power consumption The design challenge consists in finding a trade-off between the sampling frequency, the settling time and the circuit complexity since the sensor excitation plates are multiplexed between the measurement and the damping phases. In this context, a patenteddamping sequence (simultaneous damping) has been conceived to improve the damping efficiency over the state of the art approach performances (successive damping). To investigate the feasibility of the novel electrostatic damping control architecture, several mathematical models have been developed and the settling time method is used to assess the damping efficiency. Moreover, a new method that uses the multirate signal processing theory and allows the system stability study has been developed. This very method is used to conclude on the loop stability for a certain sampling frequency and loop gain value. Next, a 0.18μm CMOS implementation of the entire accelerometer signal chain is designed and validated.

La miniaturisation des circuits intégrés se poursuit de nos jours avec le développement de technologies toujours plus fines et denses. Elle permet une intégration des circuits toujours plus massive, avec des performances plus élevées et une réduction des coûts de production. La réduction de taille des circuits s'accompagne aussi d'une augmentation de leur sensibilité électrique. L'électronique automobile est un acteur majeur dans la nouvelle tendance des véhicules autonomes. Ce type d'application a besoin d'analyser des données et d'appliquer des actions sur le véhicule en temps réel. L'objectif à terme est d'améliorer la sécurité des usagers. Il est donc vital de garantir que ces modules électroniques pourront effectuer leurs tâches correctement malgré toutes les perturbations auxquelles ils seront exposés. Néanmoins, l'environnement automobile est particulièrement sévère pour l'électronique. Parmi tous les stress rencontrés, les décharges électrostatiques (ESD - Electrostatic Discharge) sont une importante source d'agression électrique. Ce type d'évènement très bref est suffisamment violent pour détruire des composants électroniques ou les perturber pendant leur fonctionnement. Les recherches présentées ici se concentrent sur l'analyse des défaillances fonctionnelles. À cause des ESD, des fonctions électroniques peuvent cesser temporairement d'être opérantes. Des méthodes d'analyse et de prédiction sont requises au niveau-circuit intégré afin de détecter des points de faiblesses susceptibles de générer des fautes fonctionnelles pendant l'exposition à un stress électrostatique. Différentes approches ont été proposées dans ce but. Une méthode hiérarchique de modélisation a été mise au point afin d'être capable de reproduire la forme d'onde ESD jusqu'à l'entrée du circuit intégré. Avec cette approche, chaque élément du système est modélisé individuellement puis son modèle ajouté au schéma complet. Un cas d'étude réaliste de défaillance fonctionnelle d'un circuit intégré a été analysé à l'aide d'outils de simulation. Afin d'obtenir plus de données sur cette faute, une puce de test a été développée, contenant des structures de surveillance et de mesure directement intégrées dans la puce. La dernière partie de ce travail de recherche est concentrée sur le développement de méthodes d'analyse dans le but d'identifier efficacement des fautes par simulation. Une des techniques développées consiste à modéliser chaque bloc d'une fonction individuellement puis permet de chaîner ces modèles afin de déterminer la robustesse de la fonction complète. La deuxième méthode tente de construire un modèle équivalent dit boite-noire d'une fonction de haut-niveau d'un circuit intégré. Ces travaux de recherche ont mené à la mise au point de prototypes matériels et logiciels et à la mise en évidence de points bloquants qui pourront constituer une base pour de futurs travaux. / Miniaturization of electronic circuits continues nowadays with the more recent technology nodes being applied to diverse fields of application such as automotive. Very dense and small integrated circuits are interesting for economic reasons, because they are cheaper to manufacture in mass and can pack more functionalities with elevated performances. The counterpart of size reduction is integrated circuits becoming more fragile electrically. In the automotive world, the new trend of fully autonomous driving is seeing tremendous progress recently. Autonomous vehicles must take decisions and perform critical actions such as braking or steering the wheel. Those decisions are taken by electronic modules, that have now very high responsibilities with regards of our safety. It is important to ensure that those modules will operate no matter the kind of disturbances they can be exposed to. The automotive world is a quite harsh environment for electronic systems. A major source of electrical stress is called the Electrostatic Discharge (ESD). It is a very sudden flow of electricity of large amplitude capable of destroying electronic components, or disturb them during their normal operation. This research focuses on functional failures where functionality can be temporarily lost after an ESD with various impact on the vehicle. To guarantee before manufacturing that a module and its components will perform their duty correctly, new analysis and prediction methods are required against soft-failures caused by electrostatic discharges. In this research, different approaches have been explored and proposed towards that goal. First, a modelling method for reproducing the ESD waveforms from the test generator up to the integrated circuit input is presented. It is based on a hierarchical approach where each element of the system is modelled individually, then added to the complete setup model. A practical case of functional failure at silicon-level is analyzed using simulation tools. To acquire more data on this fault, a testchip has been designed. It contains on-chip monitoring structures to measure voltage and current, and monitor function behavior directly at silicon-level. The last part of this research details different analysis methods developed for identifying efficiently functional weaknesses. The methods rely heavily on simulation tools, and prototypes have been implemented to prove the initial concepts. The first method models each function inside the chip individually, using behavioral models, then enables to connect the models together to deduce the full function's robustness. It enables hierarchical analysis of complex integrated circuit designs, to identify potential weak spots inside the circuit that could require more shielding or protection. The second method is focused on constructing equivalent electrical black box models of integrated circuit functions. The goal is to model the IC with a behavioral, black-box model capable of reproducing waveforms in powered conditions during the ESD. In summary, this research work has led to the development of several hardware and software prototypes. It has also highlighted important modelling challenges to solve in future works to achieve better functional robustness against electrostatic discharges.

This diploma thesis is focused on two parts. The first one deals with rheological behavior of sodium carboxymethylcellulose (CMC-Na) solutions in the presence of sodium and calcium ions. The solutions of various concentrations were prepared by solubilization in aqueous solutions of NaCl or CaCl2. The effect of monovalent and bivalent ions on apparent viscosity and viscoelastic properties of these solutions was studied. It was found that in the case of low concentrations of CMC-Na in the sample (up to 0.5% w/w) the elastic character increases. At the same time the stiffness of the sample is higher with higher concentration of calcium ion in the solution. This increase might indicate the formation of gel network. On the other hand the viscosity of these solutions decreases with higher concentration of calcium ions. In case of solutions with concentration higher than 1.5% w/w changes of viscosity did not happen by influence of addition ions. Rheological behavior was compared also with solutions prepared without adding an electrolyte as well as with acid form of carboxymethylcellulose (CMC-H). In terms of second part the molecular dynamic simulations of hyaluronan tetramer both sodium and calcium in aqueous medium were performed. Structure and arrangement of water molecules in the surrounding of hyaluronan chain were studied. Structure was described by formalism of radial distribution functions. In the case of system containing sodium ions only, the obtained results are in accordance with earlier published data. Presence of calcium ions does not cause qualitative changes during the radial distribution functions in comparison with the system with sodium ions.