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This thesis focuses on the use of a design of experiment approach to examine the significance of process factors and interactions on the fabrication of micro- textured surfaces. The micro-textured surfaces examined contain pillar and hole features ranging from 80 – 2 micrometers in diameter. The processes examined are the deep reactive ion etching of silicon wafers for the production of silicon mould inserts and the micro-injection moulding of polypropylene, high density polyethylene and 316LS stainless steel replicate samples of the silicon mould insert. During the deep reactive ion etching of the silicon wafers the design of experiment approach was used to determine the significant of platen power, C4F8 gas flow and switching times to the presence of pillar undercut of 10 x 10, 5 x 5 and 2 x 2 micrometer pillars. Undercuts occur when the pillar base has a smaller cross-section than the apex of the pillar. Switching times was found to be the only statistically significant parameter for both 10 x 10 and 5 x 5 micrometer pillars. The design of experiment approach is used in the micro-injection moulding of polypropylene, high density polyethylene and 316LS stainless steel replicates to examine the significance of mould temperature, cooling time, holding pressure and injection speed on the part and buffer mass of the produce samples, the height and width of pillar on the replicate surfaces and the variation of the replicated pillars height and width from the original silicon mould insert. Examination of the high density polyethylene replicates found that mould temperature was the most significant factor regarding pillar dimensions (and variation from the silicon mould insert) across the range of pillar sizes. Upon examination of the polypropylene replicates it was found that the factor of most significance on pillar dimensions varied across the different pillar sizes. Holding pressure was identified as the most significant factor with regards to the 53 x 29 and 19 x 80 micrometer pillars. Injection speed was found to be most significant for the 25 x 25 and 19 x 29 micrometer pillars. Cooling time was found to be most significant with regards to the 30 x 10, 25 x 10, 20 x 10 and 15 x 10 micrometer pillars. While ii mould temperature was found to be most significant for the 20 x 20, 15 x 15 and 10 x 30 micrometer pillars. The interaction between mould temperature and injection speed was also found to be the most significant factor with regards to the 43 x 29 and 25 x 30 micrometer pillars. Examination of the 316LS replicates found that mould temperature was the most significant factor regarding pillar dimensions for 80 x 80 and 19 x 80 micrometer pillars. While holding pressure was found to be most significant to the 29 x 29 micrometer pillars and injection speed was identified as most significant to the 53 x 80 micrometer pillars. The samples produced during the design of experiment investigations were then used to examine the effect of surface texturing on droplet behaviour. Droplet contact angles were examined on polypropylene, high density polyethylene and silicon samples structured with 10 – 2 micrometer pillar. Initial droplet contact angles were found to be higher on the polypropylene samples than the high density polyethylene or silicon samples. With the lowest initial contact angles being found for the silicon inserts. Droplet ‘channelling’ and evaporation were examined on silicon, polypropylene, high density polyethylene and 316LS samples structured with micro-channel surface pillars and holes ranging from 80 – 2 micrometer in diameter. Contact pinning of the droplet to the surface via the three- phase contact-line was noted during observations of droplet ‘channelling’. This pinning effect was observed at all sample tilt angles (30 - 90 o ). With regards to droplet evaporation, the droplets were noted to evaporate evenly (with no or limited contact pinning) on all unstructured surfaces and the surfaces structured with hole features. On the surfaces structured with pillar features, the droplets appeared too evaporated along the surface gradient from the smallest pillars to the largest.

Trimesoyl chloride (TMC) crosslinked poly(vinyl alcohol) (PVA) / chitosan (CS) membranes and synthetic polyimide membranes were prepared for pervaporation dehydration of isopropanol and gas separation. PVA membranes were interfacially crosslinked with different amounts of TMC/hexane, and the degree of crosslinking was characterized by Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and water uptake. The asymmetric structure of the PVA-TMC membranes was revealed by FTIR-ATR. Thermal analysis was performed to understand the pyrolysis mechanism, which was supposed to be a combination of elimination of water and/or trimesic acid followed by breakage of the main chain. Water permeation and pervaporation dehydration of isopropanol were conducted, and the results showed that PVA-3TMC had the best overall pervaporation properties among the four PVA-TMC membranes studied. Sorption properties and pervaporation behavior of the PVA-3TMC membrane were investigated. The effects of water/isopropanol on the polymer matrix and the possible change of the degree of crystallinity induced by the sorbed water were believed to account for the sorption properties. For water permeation and pervaporation dehydration of isopropanol in a heating-cooling cycle, the permeation flux did not change significantly, and the selectivity was improved by the formation of crystallites during the heating run. For pervaporation in the diluting and concentrating runs at 60 °C, there was no change in the membrane permeability. Chitosan membranes were interfacially crosslinked in TMC/hexane with different crosslinking time. The membrane with a higher degree of crosslinking showed a higher degree of swelling in water at room temperature. A two-stage thermal decomposition mechanism was proposed based on thermal analyses. Pure gas permeation was performed with CO2 and N2 at room temperature, and CS-TMC-2 showed the best performance, with a CO2 permeability of ~163 Barrer and a CO2/N2 permeability ratio of ~42. Pervaporation was carried out for dehydration of isopropanol with the unconditioned and conditioned membranes, and the CS-TMC-3 membrane showed the best pervaporation performance. Pervaporation and gas separation properties were affected by the crosslinking-induced relaxation and the mobility/packing properties of the CS-TMC matrices. 4,4'-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA)-based and 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride (BPADA)-based copolyimides were synthesized from one-step high-temperature polymerization in m-cresol. Polymers were characterized with Gel Permeation Chromatography (GPC), FTIR, Nuclear Magnetic Resonance Spectroscopy (NMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Surface free energies and interfacial free energies were calculated from contact angles to characterize hydrophilicity of the polyimide membranes. Gas permeation properties of 6FDA-based copolyimide membranes were studied with N2, O2, H2, He and CO2, and pervaporation dehydration of isopropanol was performed with 6FDA-based and BPADA-based membranes. An empirical linear moiety contribution approach was proposed, and the moiety contribution factors were used to illustrate the effects of dianhydrides and diamines on permselectivities of the copolyimide membranes. Bulky side groups, flexibility of polymer main chains, structures of monomer moieties, and interactions between gas molecules and polymer chains were shown to affect gas permselectivities, while in pervaporation, both sorption and diffusion properties were affected by the interactions between penetrants and polymer matrices as well as the steric effects of monomer moieties.

Trimesoyl chloride (TMC) crosslinked poly(vinyl alcohol) (PVA) / chitosan (CS) membranes and synthetic polyimide membranes were prepared for pervaporation dehydration of isopropanol and gas separation. PVA membranes were interfacially crosslinked with different amounts of TMC/hexane, and the degree of crosslinking was characterized by Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and water uptake. The asymmetric structure of the PVA-TMC membranes was revealed by FTIR-ATR. Thermal analysis was performed to understand the pyrolysis mechanism, which was supposed to be a combination of elimination of water and/or trimesic acid followed by breakage of the main chain. Water permeation and pervaporation dehydration of isopropanol were conducted, and the results showed that PVA-3TMC had the best overall pervaporation properties among the four PVA-TMC membranes studied. Sorption properties and pervaporation behavior of the PVA-3TMC membrane were investigated. The effects of water/isopropanol on the polymer matrix and the possible change of the degree of crystallinity induced by the sorbed water were believed to account for the sorption properties. For water permeation and pervaporation dehydration of isopropanol in a heating-cooling cycle, the permeation flux did not change significantly, and the selectivity was improved by the formation of crystallites during the heating run. For pervaporation in the diluting and concentrating runs at 60 °C, there was no change in the membrane permeability. Chitosan membranes were interfacially crosslinked in TMC/hexane with different crosslinking time. The membrane with a higher degree of crosslinking showed a higher degree of swelling in water at room temperature. A two-stage thermal decomposition mechanism was proposed based on thermal analyses. Pure gas permeation was performed with CO2 and N2 at room temperature, and CS-TMC-2 showed the best performance, with a CO2 permeability of ~163 Barrer and a CO2/N2 permeability ratio of ~42. Pervaporation was carried out for dehydration of isopropanol with the unconditioned and conditioned membranes, and the CS-TMC-3 membrane showed the best pervaporation performance. Pervaporation and gas separation properties were affected by the crosslinking-induced relaxation and the mobility/packing properties of the CS-TMC matrices. 4,4'-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA)-based and 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride (BPADA)-based copolyimides were synthesized from one-step high-temperature polymerization in m-cresol. Polymers were characterized with Gel Permeation Chromatography (GPC), FTIR, Nuclear Magnetic Resonance Spectroscopy (NMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Surface free energies and interfacial free energies were calculated from contact angles to characterize hydrophilicity of the polyimide membranes. Gas permeation properties of 6FDA-based copolyimide membranes were studied with N2, O2, H2, He and CO2, and pervaporation dehydration of isopropanol was performed with 6FDA-based and BPADA-based membranes. An empirical linear moiety contribution approach was proposed, and the moiety contribution factors were used to illustrate the effects of dianhydrides and diamines on permselectivities of the copolyimide membranes. Bulky side groups, flexibility of polymer main chains, structures of monomer moieties, and interactions between gas molecules and polymer chains were shown to affect gas permselectivities, while in pervaporation, both sorption and diffusion properties were affected by the interactions between penetrants and polymer matrices as well as the steric effects of monomer moieties.

The use of hydrophobic surfaces is important for many processes both in nature and industry. Interactions between hydrophobic species play a key role in industrial applications such as water-cleaning procedures and pitch control during papermaking but they also give information on how to design surfaces like hydrophobic mineral pigments. In this thesis, the influence of surface properties on wetting and interaction forces has been studied. Surfaces with close-packed particles, pore arrays, randomly deposited nanoparticles as well as reference surfaces were prepared. The atomic force microscope (AFM) was utilized for force and friction measurements while contact angles and confocal Raman microscopy experiments were mainly used for wetting studies. The deposition of silica particles in the size range of nano- to micrometers using the Langmuir-Blodgett (LB) technique resulted in particle coated surfaces exhibiting hexagonal close-packing and close to Wenzel state wetting after hydrophobization. Force measurements displayed long-range interaction forces assigned to be a consequence of air cavitation. Smaller roughness features provided larger forces and interaction distances interpreted as being due to fewer restrictions of capillary growth. Friction measurements proved both the surface structure and chemistry to be important for the observed forces. On hydrophobic pore array surfaces, the three-phase contact line of water droplets avoided the pores which created a jagged interface. The influence of the pores was evident in the force curves, both in terms of the shape, in which the three-phase contact line movements around the pores could be detected, as well as the depth of the pores providing different access and amount of air. When water/ethanol mixtures were used, the interactions were concluded to be due to ethanol condensation. Confocal Raman microscopy experiments with water and water/ethanol mixtures on superhydrophobic surfaces gave evidence for water depletion and ethanol/air accumulation close to the surface. Force measurements using superhydrophobic surfaces showed extremely long-range interaction distances. This work has provided evidence for air cavitation between hydrophobic surfaces in aqueous solution. It was also shown that the range and magnitude of interaction forces could, to some extent, be predicted by looking at certain surface features like structure,roughness and the overall length scales. / <p>QC 20121011</p>

Since decades, drop impact has been a popular topic of investigation for the importance that such a phenomenology has in many different application domains.<p><p>So far, the effect of micro-particles on the drop impact morphology has been studied for a limited number of configurations and often modelled as a change in the viscosity of the carrier fluid. However, this approach has been found sometimes questionable. The aim of the thesis is to better understand the phenomenology associated with particle-laden drop impact such as the distribution of particles in splats and to extend the number of experimental configurations for particle-laden drop impact to occur.<p><p>The impact of millimetre-size particle-laden drops was investigated for hydrophilic and hydrophobic substrates. The drops were dispersions of water and round, spherical and nearly iso-dense hydrophobic particles with diameters around 200 µm and 500 µm. The substrates were transparent glass and polycarbonate plates. The impact was studied by side, bottom and angle view images in the range 148≤We≤744 and 7092≤Re≤16368.<p><p>The particles were found to suppress the appearance of singular jetting and drop partial rebound, and also cause early splashing, receding break-up and rupture. The occurrences of these phenomena depend on the impact velocity, particles’ diameter and volume fraction. The drops with 200 µm particles spread in two phases: fast and slow, caused by inertial and capillary forces, respectively. Also, the increase of volume fraction of 200 µm particle leads to a linear decrease of the maximum spreading factor caused by the inertia force on the hydrophilic and hydrophobic substrates. The comparison of our data and the existing ones for splashing led to the formulation of а new splashing criterion for particle-laden drops. The novel criterion improves upon current models in predicting the splashing threshold by introducing effect of particle volume fraction and particle wettability. The analysis of particle distribution showed that 200 µm particles formed atypical distributions in splats after the impact in contrast to 500 µm particles with random pattern. The 200 µm particles formed rings/disks and a crown-like structure on hydrophilic and hydrophobic substrates, respectively. These patterns were described by correlations.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

La peau est une interface essentielle entre le corps humain et son environnement externe. Au-delà du rôle de couche protectrice contre les agressions externes (mécaniques, thermiques, chimiques…), elle dispose de multiples fonctions de régulation comme l’absorption, la thermorégulation ou la synthèse d’hormones. L’étude de cette interface cutanée est importante, non seulement pour les spécialistes cliniques, mais également pour les chercheurs travaillant dans la compréhension des mécanismes des processus de transfert transcutanés. Longtemps considéré comme une simple couche de cellules mortes, le stratum corneum (SC, couche de la peau la plus externe) était considéré alors comme un acteur secondaire dans ces processus. Des études récentes montrent au contraire que cette couche cutanée, d’une épaisseur pouvant aller de 10 à 40 µm, joue un rôle primordial et déterminant. Ces études révèlent une architecture complexe, qui peut être représentée schématiquement par un empilement de cellules protéiniques (les cornéocytes) situées dans une matrice extracellulaire riche en lipides. Cette couche compacte est loin d’être complètement imperméable aux substances chimiques directement appliquées sur la peau. Nous proposons ici une approche physico-chimique visant à mettre en évidence les mécanismes d’interactions acide-base agissant à l’extrême surface du SC (i.e. une dizaine d’Angströms). En utilisant : i) les réactions de transfert de protons comme “sonde” et ii) une démarche multi-échelles basée sur des titrations de surface par angles de contact et par forces chimiques, nous déterminons quantitativement le rôle de chacune des composantes du SC (i.e. cornéocytes et lipides) dans ce type d’interactions. / Stratum corneum (SC) is a heterogeneous tissue composed of lipid-depleted corneocytes embedded in a lipid-enriched extracellular matrix. It comes from the epidermal differentiation of the skin. The wetting properties of this upper layer are of major interest in the understanding of interfacial phenomena, such as adhesion of microorganisms or proliferation of resident flora. Until now, the wettability behaviour has been characterized through different parameters such as surface energy, critical surface tension, or hydrophilia, via macroscopic contact angle measurements. But this method does not allow to discriminate the effect of the corneocytes with the one of the extracellular matrix on the final surface properties, because of the size of the liquid drop. This work, performed in vitro on human skin explants provided by Pierre Fabre Dermo-Cosmetics, consists in understanding the wetting properties of the SC from macroscopic and nanoscopic points of view. Initially, it is compulsory to thoroughly describe at different scales the physical chemistry of our material, i.e. in vitro SC. Then, knowing that macroscopic contact angles are sensitive to the pH of the liquid probe, the first aim of this work is to determine the “macroscopic pKa values” of the SC, both in vitro and in vivo. Consequently, dynamic contact angles are measured between test-liquid drops (aqueous solutions ranging from pH 1 to pH 13) and the SC in order to obtain the contact angle titration curve of the SC. The same procedure is applied in vivo on SC suffering from skin dryness (xerosis), the results being compared to those obtained previously on safe skin. The second purpose of this study is to reach the pKa values of the different functional groups located on the complex-cornified envelope. This consists in measuring adhesion forces between an AFM (Atomic Force Microscopy) tip (functionalized with specific groups, such as amine, carboxylic acid, hydroxyl, methyl or amide groups) and single-isolated corneocytes through buffered liquid media (ranging from pH 1 to pH 13). As previously, such titration curves are realised on corneocytes coming from safe skin, but also from dry skin. The variations observed in the contact angle titration and chemical force titration curves will be discussed in terms of acid-base, electrostatic interactions and hydrogen bondings. The comprehension of the pH-dependent properties of the SC shall provide a better understanding of the role of individual corneocytes in the final surface properties of the SC.

Le travail réalisé dans cette thèse concerne l'optimisation d’électrolytes organiques pour supercondensateur lithium-ion. Plusieurs solvants ont été sélectionnés pour la formulation de mélanges binaires ou ternaires additionnés de sel de lithium. Les propriétés physicochimiques et électrochimiques de ces électrolytes contenant LiTFSI ou LiPF6 (EC/DMC ; dinitrile/DMC ; EC/Ester/3DMC, EC/MiPC/3DMC) ont été caractérisées en vue de leur utilisation dans des dispositifs hybrides, l’objectif étant de satisfaire à la fois aux exigences des matériaux graphite et carbone activé. Les interactions solvant-solvant et solvant-sel des électrolytes ont été étudiées à partir des théories de Jones-Dole, Stocks-Einstein et Bjerrum appliquées aux mesures de viscosités et conductivités. Cela a permis de développer des modèles prédictifs de la conductivité dans des cas de solvants purs ou de mélanges simples. La deuxième partie de cette thèse a été dédiée à la réalisation de demi-cellules avec différentes formulations d'électrolytes à la fois sur carbone activé et sur graphite. Les interfaces électrodes/électrolytes et séparateurs/électrolytes ont été étudiées. La corrosion des collecteurs en Al en présence de LiTFSI a fait l'objet d'une étude qui a permis de dégager une solution consistant en la formulation d'un électrolyte additionné de 1% d'additifs source de fluorure tel que LiPF6. Enfin, des dispositifs complets graphite/carbone activé ont été réalisés en utilisant les différents électrolytes optimisés ce qui a permis de mettre en évidence le gain en énergie (x5) pour un tel système par rapport aux supercondensateurs symétriques classiques. / The objective of this thesis is to broaden the knowledge of electrochemical, thermo physical and thermodynamic properties of different efficient and safe organic electrolytes for Lithium-ion Capacitors (LICs). Several solvent structures have been first selected to design new electrolytes based on binary or ternary solvent mixtures. These solvents were then characterized through conductivity, viscosity and electrochemical studies, in order to assess their structure and properties relationships. Based on this investigation, best compromise between mobility and ionic concentration has been evaluated to formulate the best electrolytes. Generally, it was proved that the addition of solvents with very low viscosity provides efficient electrolytes. Based on conductivity and viscosity measurements, a theoretical study on solvent-solvent and solvent-salt interactions has been then performed using different well-known equations based on Stock-Einstein, Jones-Dole and Bjerrum theories to understand, rationalize, correlate and then predict their transport properties. The second part of the study concentrated on the characterization of selected electrolytes in an asymmetric LIC prior to developing such electrolytes in any high performance asymmetric capacitor devices. In other words, the main objective of this part is to verify the compatibility of designed electrolytes with each element, e.g. electrodes (graphite, activated carbon) and current collectors (aluminum), of a LIC device. To drive such analysis, different experimental investigations between electrodes/electrolytes and between collectors/electolytes were in fact investigated. Using this strategy, asymmetric systems LICs containing a formulated organic electrolyte were fully characterized to deter mine the electrochemical performances of the designed solution in LIC conditions and then compared with those observed using classical electrolyte currently used.

Οι πίδακες πλάσματος ατμοσφαιρικής πίεσης διαδραματίζουν ολοένα και σημαντικότερο ρόλο σε διάφορες διαδικασίες επεξεργασίας και εφαρμογής του ψυχρού πλάσματος. Αυτό συμβαίνει λόγω της ιδιαίτερης ιδιότητας τους να παράγουν ενεργά φορτισμένα σωματίδια διατηρώντας τη θερμοκρασία του αερίου σε χαμηλές τιμές. Πρόσφατα, αυτό το ελκυστικό χαρακτηριστικό οδήγησε στην εκτεταμένη χρήση τους σε εφαρμογές που απαιτούν χαμηλές θερμοκρασίες, όπως στην επεξεργασία υλικών και σε βιολογικές εφαρμογές. Η μελέτη δύο τέτοιων εφαρμογών καθώς και η ανάλυση των χαρακτηριστικών εκκένωσης που λαμβάνει χώρα στο εσωτερικό ενός αντιδραστήρα παραγωγής πίδακα πλάσματος αποτελούν τους δύο κεντρικούς άξονες αυτής της διπλωματικής εργασίας. Ένας από τους κύριους στόχους του παρόντος εκπονήματος είναι ο προσδιορισμός των βέλτιστων συνθηκών λειτουργίας ενός συστήματος παραγωγής πίδακα πλάσματος. Ως επόμενο αντικείμενο μελέτης είναι η εφαρμογή ενός δεύτερου παρόμοιου συστήματος παραγωγής πίδακα πλάσματος για τροποποίηση της επιφάνειας πολυμερούς (πολυανθρακικού) με σκοπό την αύξηση της υδροφιλίας του και βελτίωση της βιοσυμβατικότητάς του. Επιχειρείται ανάλυση των μηχανισμών που καθορίζουν την αλληλεπίδραση του πίδακα πλάσματος με το πολυμερές. Τέλος, πραγματοποιείται εφαρμογή του ίδιου συστήματος για επεξεργασία λιποσωμικών μεμβρανών ως μοντέλο βιοσυστήματος. Ειδικότερα: • Στο πρώτο κεφάλαιο αναφέρονται κάποιες βασικές έννοιες και χαρακτηριστικά που αφορούν στο ψυχρό πλάσμα με έμφαση στους πίδακες ψυχρού πλάσματος και παρατίθενται διάφορα παραδείγματα αυτών που έχουν καταγραφεί στη βιβλιογραφία μέχρι σήμερα επιλέγοντας ως κριτήριο κατάταξής τους την τάση τροφοδοσίας. • Στο δεύτερο κεφάλαιο περιγράφονται αναλυτικά οι δύο πειραματικές διατάξεις πίδακα πλάσματος ατμοσφαιρικής πίεσης όπου πραγματοποιήθηκε το σύνολο των μετρήσεων. Παρουσιάζονται τα επιμέρους όργανα που χρησιμοποιήθηκαν για τη μέτρηση συγκεκριμένων μεγεθών και ταυτόχρονα παρατίθενται φωτογραφικό υλικό. Tέλος περιγράφονται δύο εφαρμογές του δεύτερου συστήματος που αφορούν στην επεξεργασία του πολυμερούς και των λιποσωμάτων και αναλύονται οι διαγνωστικές τεχνικές που εφαρμόστηκαν. • Στο τρίτο κεφάλαιο παρουσιάζεται το σύνολο των πειραματικών αποτελεσμάτων. Για τους σκοπούς αυτής της εργασίας πραγματοποιήθηκαν ηλεκτρικές και οπτικές μετρήσεις, μετρήσεις γωνιών επαφής, XPS αναλύσεις και μετρήσεις έντασης φθορισμού. • Στο τέταρτο κεφάλαιο καταγράφονται τα συμπεράσματα που προέκυψαν από τις επιμέρους μελέτες. Σημειώνονται ενδεικτικές τιμές των παραμέτρων του πρώτου συστήματος πίδακα πλάσματος για βέλτιστη λειτουργία. Επιτυγχάνεται μείωση της γωνίας επαφής έως και 49ο και τονίζεται ο πρωταρχικός ρόλος των διεγερμένων ουδέτερων και μετασταθών σωματιδίων του πίδακα πλάσματος στην επεξεργασία. Τέλος, παρατηρείται ποσοστό διάσπασης-επεξεργασίας των λιποσωμάτων έως 15%. / Non-thermal atmospheric pressure plasma jets are playing an increasingly important role in various plasma processing applications. This is because of their practical capability to achieve enhanced gas phase chemistry without the need of elevated gas temperatures. This attractive characteristic recently led to their extensive use in applications that require low temperatures, such as material processing and biomedical applications. The studies of two applications as well as the analysis of discharge characteristics inside the atmospheric pressure plasma jet are the two principal issues of this thesis. More specifically, one of the main objects of the present thesis is the determination of the optimal operation conditions for an atmospheric plasma jet system. A second, similar atmospheric plasma jet system was applied for surface modification of a polymer (polycarbonate) by increasing its wettability Τhe analysis of mechanisms governing the interaction of plasma jet with the polymer is presented. Finally, the same system was also applied for liposomes treatment considered as biosystem model. Particularly: • In the first chapter a brief report on the general characteristics of plasma is mentioned and a review of the different atmospheric pressure plasma jets developed until today is presented. The plasma jets are classified according to their power sources. • In the second chapter the two different experimental set-ups used are described in details. The specific characteristics of each atmospheric pressure plasma jet are outlined and all the others apparatus used are presented and demonstrated by means of photography. At the end, two applications of the second plasma jet are referred concerning polymer and liposome treatment with their respective diagnostics techniques. • In the third chapter the total experimental measurements are presented. For the goals of this thesis were conducted a plenty of electrical and optical measurements, contact angles measurements, XPS analyses and fluorescence intensity measurements. • In the forth chapter all the conclusions exported of each part are recorded. Firstly, the optimal operational conditions, as excluded from the experimental procedure, are recorded. It is obtained a significant decrease of contact angle until 49ο, emphasizing on the dominant role of the reactive excited neutrals and metastables species. Also modification of the liposome membranes is observed at the percentage of 15%.

This thesis presents elliptical rolling contact joints as an alternative to circular rolling contact and conventional revolute joints where high quality force transmission "low friction and backlash" with variable output are desired. Parameters specific to the joint and its position are developed in terms of relative link angles and elliptical surface geometry. These parameters are used to generate the basic forward kinematics for elliptical rolling link toggle mechanisms with oscillatory motion and high mechanical advantage. As large compressive loads are characteristic of such mechanisms, stress conditions are identified and principles for joint stability with variable, precision outputs are discussed. Finally, application is made to self-adjusting passive force closures with a case study of the MUSCLE Brake (Multi-toggle Self-adjusting Connecting-Linked Electromechanical) disc brake caliper. Elliptical rolling contact joints are shown to offer several benefits over circular rolling contact, including: reduced Hertz contact stresses and flexure bending stresses, variable output velocity, maximum use of contact interface by distributing small rotations across surfaces of small curvature, reduced forces on stabilizing members, increased mechanical advantage due to eccentricity, and no-slip pure rolling provided exclusively by connecting links (or flexures) without the need for gear teeth or friction.