Portail HAL UHA (Université de Haute-Alsace)
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Room Temperature Synthesis and Photopatterning of Mesoporous Titanium Dioxide Thin Films
No full textInternational audienceWe report a photochemical strategy for fabricating mesoporous TiO 2 thin films that combines deep-UV (193 nm) photolithography with block copolymer (BCP) self-assembly. This dual top-down/bottom-up approach enables direct patterning and mineralization at room temperature, without thermal annealing, offering a scalable and energy-efficient alternative to conventional sol-gel processing. By tailoring the BCP concentration, titanium-to-ethylene oxide molar ratio, and polymer architecture, we achieved highly uniform mesoporous monolayers with tunable pore size and film thickness. FTIR and SEM analyses confirm the selective degradation of the PS and PEO blocks under UV exposure. Notably, the PEO degradation is significantly enhanced in the presence of titanium oxo-clusters, attributed to the photocatalytic activity of the Ti precursor under DUV irradiation. We further demonstrate spatially controlled structuring via photolithographic masks, enabling micro-and nanopatterned oxide films with hierarchical architectures. This method allows for precise control over both porosity and lateral geometry, expanding the design space for functional oxide coatings. Our findings open new avenues for the fabrication of advanced hierarchical TiO 2based materials for applications in photonics, sensing, and nanotechnology, while contributing to the broader development of low-temperature, light-assisted material processing
Biomaterial-driven immune modulation in volumetric muscle loss regeneration
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Etude de la croissance de nanorubans de Ge sur un cristal d’AI(110)
No full textThis thesis investigates the growth and characterization of germanium (Ge) nanoribbons deposited by molecular beam epitaxy (MBE) on an Al(110) substrate. This represents the first experimental study of this system, combining low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS) to characterize the formation, organization, and stability of the nanoribbons. At low coverage, Ge forms an alloy with Al exhibiting a (2×1) reconstruction, while at higher coverage, nanoribbons are formed with widths of 1.3–1.4 nm and with an asymmetric “Y” motif at the top of the nanoribbon. The atomic structure remains stable for deposition temperatures between 85 °C and 255 °C. XPS analysis reveals a substrate-induced metallic character of Ge and chemical stability of Al. These findings highlight the thermal and structural stability of the nanoribbons, providing promising perspectives for nanoelectronic and optoelectronic applications.Ce travail de thèse explore la croissance et la caractérisation de nanorubans de germanium (Ge) déposés par épitaxie par jets moléculaires (MBE) sur un substrat d’aluminium Al(110). Il s’agit de la première étude expérimentale consacrée à ce système, combinant diffraction d’électrons lents (LEED), microscopie à effet tunnel (STM) et spectroscopie de photoélectrons X (XPS) pour caractériser la formation, l’organisation et la stabilité des nanorubans. À faible recouvrement, le Ge forme un alliage avec l’Al et une reconstruction (2×1), tandis qu’à recouvrement plus élevé apparaissent des nanorubans organisés avec une largeur de 1,3–1,4 nm et un motif interne asymétrique en « Y ». La structure atomique reste stable pour des températures de dépôt entre 85 °C et 255 °C. L’analyse XPS révèle un caractère métallique induit par le substrat du Ge et une stabilité chimique de l’Al. Ces résultats démontrent la stabilité thermique et structurale des nanorubans, ouvrant des perspectives pour des applications en nanoélectronique et optoélectronique
Contribution à l’amélioration du fraisage des composites à renfort fibreux : approche expérimentale du détourage de stratifiés verre/époxy par outils à taille diamant
No full textIn the manufacturing process of fiber-reinforced polymer parts, milling operations are generally necessary after curing. Mastering these operations is essential to guarantee the quality of the finished part. These operations raise particular challenges, not only because of the heterogeneity and anisotropy of the material, but also because of the nature of its constituents. As a result, specific cutting tool geometries are often used to optimize the machining quality, notably the diamond-interlocking tool geometry. This work investigates the edge trimming of glass fiber-reinforced polymers using this type of tool. Firstly, a multi-parameter study of the influence of fiber orientation on cutting is proposed for unidirectional composites. Cutting forces, temperature during machining and edge trimming quality are analyzed. The results reveal cutting mechanisms similar to orthogonal cutting, despite the complex geometry of the tool. Secondly, the impact of cutting parameters (radial engagement, feed per revolution and cutting speed) is investigated for unidirectional composites. In particular, the results show that the effect of these parameters depends on the cutting mechanism involved. Thirdly, the study is extended to the edge trimming of multidirectional composites. In particular, a strategy is proposed to avoid defects occurrence on outer plies.La fabrication de pièces en polymères renforcés de fibres nécessite généralement des opérations de fraisage après l’étape de mise en œuvre. Leur maitrise est essentielle pour garantir la qualité de la pièce finie. Ces opérations posent des problématiques particulières, en raison de l’hétérogénéité et de l’anisotropie du matériau, mais également de par la nature même de ses constituants. Ainsi, des géométries d’outil coupant spécifiques sont souvent utilisées pour optimiser la qualité de la coupe, notamment la géométrie à taille diamant. Le détourage de polymères renforcés de fibres de verre avec ce type d’outil est investigué dans ce travail. Premièrement, une étude multi-paramètres de l’influence de l’orientation des fibres sur la coupe est proposée dans le cas de composites unidirectionnels. Les efforts, la température pendant usinage ainsi que la qualité du détourage sont analysés. Les résultats font apparaitre des mécanismes de coupe similaires à la coupe orthogonale, malgré la géométrie complexe de la fraise. Deuxièmement, l’impact des conditions de coupe (engagement radial, avance par tour et vitesse de coupe) est investigué pour des composites unidirectionnels. Les résultats montrent notamment que l’effet de ces paramètres dépend du mécanisme de coupe qui est impliqué. Troisièmement, l’étude est élargie au détourage de composites multidirectionnels. En particulier, une stratégie est proposée pour éviter l’apparition de défauts sur les plis extérieurs
Toward predicting silver ion binding in proteins
No full textInternational audienceThe binding of metal ions in proteins is often crucial for their function and hence for life. Silver is known to possess antimicrobial properties, yet little is known about the exact molecular mechanism of action. Based on the silver binding tetrapeptide moieties HX1X2M, and MX1X2H found in the silver efflux pump protein SilE, we studied the influence of the individual amino acids X1and X2and found trends that may be important in general metal ion binding in proteins
Evaluation par acquis et projet cœur de métier en formation d'ingénieur en Mécanique à l'ENSISA
No full textInternational audienceEvaluation par acquis et projet cœur de métier en formation d'ingénieur en Mécanique à l'ENSIS
Mechanistic and physicochemical insights into the photoactivation pathways of a charge transfer ATRP photoinitiator
No full textInternational audiencePhotochemistry has revolutionized the chemical industry by introducing sustainable and energy‐efficient processes that are vital for the manufacture of advanced materials which align with Industry 4.0 standards. Among photochemical techniques, photopolymerization stands out as a rapid, controlled, and eco‐friendly approach, making it particularly suitable for applications like 3D printing. This research in two‐photon‐induced photopolymerization for 3D microfabrication led to groundbreaking performance, thanks to the use of custom π‐ extended molecular architectures as photoinitiators. Building on these results, a photoactivable initiation system for photoinduced‐atom transfer radical polymerization (photoATRP) is now reported using a similar π ‐extended photoinitiator. Through comprehensive optimization, we successfully created a functional multicomponent photoinitiating system, with its detailed mechanism thoroughly established in solution. By covalently attaching alkyl halides to glass surfaces, we were able to implement the surface‐induced photo‐ATRP technique to create customized brush polymer architectures. This work not only advances the understanding of photoATRP mechanisms but also introduces new strategies for functional surface engineering, with potential applications in two‐photon‐induced surface modification of 3D/4D structures via photoATRP
Should Customers Be Compensated for Their Personal Data? Results from a Mixed-Methods Study
No full textThème du congrès : « The Role of Marketing in Reshaping the Dynamic Landscape of Business: Innovation, Sustainability, and Legitimacy »International audienc
Engineering nitrogen-doped porous carbon positive electrodes for high-performance sodium-ion capacitors: the critical role of porosity, structure and surface functionalities
No full textInternational audienceSodium-ion capacitors are increasingly gaining momentum thanks to their high energy and power densities. However, there is still a lack of understanding of porous carbon positive electrode properties that affect their electrochemical performance. To address this challenge, carbon materials with controlled porosity, structure and surface functionalities are strongly required. Herein, we report the synthesis of nitrogen-doped porous carbons (NDPCs) by a combined soft-salt templating approach, that allows to achieve various nitrogen doping levels (up to 8 at%) via precursor amount modification. This results in materials with ultrahigh specific surface area (up to 2412 m2 g−1) and finely tuned pore size (up to 0.92 nm) matching the desolvated PF6− anion sorption requirement of 0.8 nm, along with controlled graphitization induced by the salt type. The materials exhibit specific capacities ranging from 83 to 159 mA h g−1vs. Na/Na+, higher than that of commercial carbons. From positive linear correlations, it was identified that the improved capacity is driven by the large specific surface area, substantial microporous volume with appropriate pore size, and structural defects, which enhance ion adsorption and promote enhanced specific capacity. However, the capacity retention is improved by the mesoporous volume and graphitic domains. Moreover, the surface pseudocapacitive interactions involving Na+ and PF6− ions could be associated with specific oxygen-containing groups (phenol/ethers and anhydride) and nitrogen species (pyridinic-N/pyrrolic-N). The dual carbon full-cell configuration consisting of a hard carbon and N-doped carbon achieves a high energy density of 209 W h kg−1 and a maximum power density of 5040 W kg−1 with ∼100% coulombic efficiency
Cooperative Aerial-Ground Vehicle Rendezvous with Integrated Obstacle Avoidance
No full textInternational audienceThis work addresses the integration of simultaneousobstacle avoidance for an Unmanned Aerial Vehicle(UAV) and an Unmanned Ground Vehicle (UGV) operatingcooperatively to rendezvous at a predefined location. A distributedconsensus-based architecture is proposed to guide thevehicles toward their designated rendezvous point. Additionally,a virtual force-based obstacle avoidance method is employedfor both vehicles. A comparison is conducted with an existingcontrol approach from the literature extended to incorporateobstacle avoidance. Simulation results are provided showing theability of the presented controllers to achieve rendezvous whilesimultaneously avoiding obstacles