No / This study investigates the influence of length scale effects (micro- and macro-injection molded parts) and mold temperature on the epitaxial growth and morphological characteristics in injection-molded bars of isotactic polypropylene (iPP)/high-density polyethylene (HDPE) blends. After preparing the blends with an iPP content of 70 wt% via melt extrusion, the injection-molded bars were formed using both micro and conventional injection molding. Samples were subsequently prepared from the moulded components to allow investigation of the internal morphology using wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and polarized light microscopy (PLM). The results indicated that the matching of micro scale and appropriate mold temperature was most favorable for epitaxial crystallization. The micro-parts had a large fraction of shear layer compared with macro-parts. The SEM observations showed that the shear layer of the former consisted of a highly oriented shish-kebab structure. Moreover, the effects of different methods of injection molding on the morphological characteristics of the micro-parts and macro-parts in different layers were elucidated in detail using PLM and SEM.

Yes / Micro-injection moulding (μIM) stands out as preferable technology to enable the mass production of polymeric components with micro- and nano-structured surfaces. One of the major challenges of these processes is related to the quality assurance of the manufactured surfaces: the time needed to perform accurate 3D surface acquisitions is typically much longer than a single moulding cycle, thus making impossible to integrate in-line measurements in the process chain. In this work, the authors proposed a novel solution to this problem by defining a process monitoring strategy aiming at linking sensitive in-line monitored process variables with the replication quality. A nano-structured surface for antibacterial applications was manufactured on a metal insert by laser structuring and replicated using two different polymers, polyoxymethylene (POM) and polycarbonate (PC). The replication accuracy was determined using a laser scanning confocal microscope and its dependence on the variation of the main μIM parameters was studied using a Design of Experiments (DoE) experimental approach. During each process cycle, the temperature distribution of the polymer inside the cavity was measured using a high-speed infrared camera by means of a sapphire window mounted in the movable plate of the mould. The temperature measurements showed a high level of correlation with the replication performance of the μIM process, thus providing a fast and effective way to control the quality of the moulded surfaces in-line. / MICROMAN project (“Process Fingerprint for Zero-defect Net-shape MICRO MANufacturing”, http://www.microman.mek.dtu.dk/) - H2020 (Project ID: 674801), H2020 agreement No. 766871 (HIMALAIA), H2020 ITN Laser4Fun (agreement No. 675063)

Yes / Inspired from the low wetting properties of Lotus leaves, the fabrication of dual micro/nano-scale topographies is of interest to many applications. In this research, superhydrophobic surfaces are fabricated by a process chain combining ultrashort pulsed laser texturing of steel inserts and injection moulding to produce textured polypropylene parts. This manufacturing route is very promising and could be economically viable for mass production of polymeric parts with superhydrophobic properties. However, surface damages, such as wear and abrasion phenomena, can be detrimental to the attractive wetting properties of replicated textured surfaces. Therefore, the final product lifespan is investigated by employing mechanical cleaning of textured polypropylene surfaces with multipurpose cloths following the ASTM D3450 standard. Secondly, the surface damage of replication masters after 350 injection moulding cycles with glass-fiber reinforced polypropylene, especially to intensify mould wear, was investigated. In both cases, the degradation of the dual-scale surface textures had a clear impact on surface topography of the replicas and thus on their wetting properties, too. / Europe Union H2020 research and innovation programme.

Yes / The structural formation and development of isotactic polypropylene (iPP) upon the micro-injection molding process was investigated at different mold temperatures and molecular weights utilizing a real-time synchrotron radiation small angle X-ray scattering (SAXS) technique combined with a customized micro-injection molding apparatus. Shish-kebab structure and parent-daughter lamellae were found to be formed during micro-injection molding for all iPP samples. In the case of kebab lamellae, a considerable growth in the long period and in the average thickness of lamellar crystallites and amorphous domains is observed at initial stages of crystallization for samples molded at varying temperatures. This effect is caused by the successive formation of thin lamellae in the outer layer and thick lamellae in the inner layer during the manufacturing process as evidenced by the spatial distribution of the crystalline lamellae across the thickness. In addition, the length of the shish formation increases remarkably at the onset of crystallization, the extent of which is dependent on the mold temperature. Despite the large changes of the lamellar stacks and the shish misorientation, the final length of the shish remains essentially unchanged when varying mold temperature. Since there is a critical orientation molecular weight above which the chains are stretched and oriented to form stable shish, the iPP sample with a low molar mass exhibits an overall decrease in the scattering intensity of SAXS patterns compared to the high molecular weight polypropylene. / This work is financially sponsored by the National Key R&D Program of China (2018YFB0704200), National Natural Science Foundation of China (21674119, 21790342 and 51525305), and Royal Society Newton Advanced Fellowship, United Kingdom (NA150222).

We introduce Sonifind, a micro guidance system implemented on a smartphone that uniquely integrates computer vision and spatial audio intended to assist users who are visually impaired. Currently, micro guidance systems require head-mounted displays and various hardware, limiting their practicality for everyday use. Our system employs an off-the-shelf computer vision library and a smartphone to interpret the user's surroundings and provide intuitive spatial audio cues for real-time guidance. We conducted a between-subjects study with sighted, blindfolded participants to evaluate the learnability, performance, and user satisfaction of Sonifind using two different versions of the system to further inform our ongoing design considerations. We found that the first version of our system (2D Feedback System) with directional (yaw) and depth (translation) audio cues resulted in quicker learnability but worse overall performance. In the second version of our system (3D Feedback System) with vertical axis guidance (pitch), we observed greater user satisfaction but a larger learning curve. These findings suggest that Sonifind has the potential to provide an effective and user-friendly navigation aid for non-sighted individuals, facilitating greater independence and mobility.

Research on adolescent drinking shows that younger people are at greater risk of developing behavioral deficiencies that can be detrimental to their social relationships and health over time. Recent research has shown that changes within the microbiome-gut-brain axis (MGB) can affect social behavior. These changes involve microbiota populations that influence addictive behaviors after prolonged substance intake through neurochemical shifts that extend through the nervous, circulatory, and immune system. Using Massey's biosocial model, I aim to expand on the relationship between the MGB axis, social behavior, and adolescent alcohol use disorder through a meta-theoretical approach. I explore the strengths and shortcomings of Massey's biosocial model of segregation and stratification and its use of the allostatic load model, telomere length, and gene exposure to develop a stronger theoretical concept using the micro-gut-brain axis as a conceptual foundation. Can the MGB-axis model be used to identify potential pathways in which alcohol use disorder (AUD) persists from adolescence to adulthood? I find that adolescent drinking leads to changes in microbiota populations that are known to influence AUDs and increases the development of diseases such as liver disease and its effects on social behavior. The MGB axis can help us understand the effects of substance and dietary habits on disease and illness by connecting life science knowledge and sociological perspectives. With this modern application of cognitive sociology, I have shown that future research on addictive behaviors should consider the application of biomarker data to further expand on new theoretical and methodological approaches in the study of disease and addiction.

Thèse ou mémoire avec insertion d'articles. / L'obtention d'un aperçu microscopique de la structure interne et de la biologie de la glace de mer a traditionnellement été limitée à des méthodes d'échantillonnage destructives et intrusives par carottes de glace. Dans cette étude, nous présenterons un système révolutionnaire d'imagerie microscopique in situ conçu pour étudier les microstructures internes et les micro-organismes présents dans la glace de mer, sans avoir recours aux techniques d'échantillonnage conventionnelles. Ce nouveau système offre une vue inédite en temps réel de la vie dans cet environnement unique. La nature complexe et hétérogène de la glace de mer, avec sa matrice de glace, ses canaux de saumure, ses bulles d'air et ses diverses impuretés, a posé de nombreux défis d'ingénierie pour la mise au point de ce système d'imagerie. Le système développé est un microscope de terrain à multi-illumination et à géométrie d'imagerie réflective. Nous avons effectué des tests de validation dans la glace de mer de première année entre le 20 avril et le 3 mai 2023 dans la baie de Baffin. Malgré la fragilité inhérente à la matrice de la glace de mer, notre système d'imagerie nous a permis de capturer des images de microstructures et de micro-organismes avec des détails satisfaisants. La conception matérielle et logicielle de l'endoscope est présentée ainsi que les résultats de l'acquisition des images de la microstructure et de micro-organismes. Ces résultats démontrent collectivement le potentiel de ce nouveau système d'imagerie microscopique in situ à révolutionner la façon dont nous étudions la glace de mer et à fournir une compréhension plus approfondie de ses microstructures complexes et de ses micro-organismes vivants. Cette innovation recèle un immense potentiel pour faire progresser notre compréhension de la dynamique écologique, des processus biogéochimiques et des adaptations des micro-organismes dans la glace de mer. / Gaining microscopic insight into the internal structure and biology of sea ice has traditionally been limited to destructive and intrusive ice core sampling methods. In this study, we introduce a groundbreaking in situ microscopic imaging system designed to study the internal micro-structures and microorganisms within sea ice, all without the need for conventional sampling techniques. This novel system offers a never-before-seen real-time view of life within this unique environment. The complex and heterogeneous nature of sea ice, including its water crystal lattice, brine channels, air bubbles, and various impurities, presented numerous engineering challenges for developing this imaging system. The developed system is a field microscope with multi-illumination and *en-face* geometry. We conducted validations tests in first-year Arctic interior sea ice between April 20th and May 3rd 2023 in Baffin Bay. Despite the inherent fragility of the sea-ice matrix, our imaging system allowed us to capture images of microstructures and biota in satisfying detail. The hardware and software design of the endoscope are presented along with acquisition results of the microstructure and biota images. These findings collectively demonstrate the potential for this new in situ microscopy imaging system to revolutionize the way we study sea ice and provide a deeper understanding of its complex microstructures and living microorganisms. This innovation holds immense potential for advancing our understanding of ecological dynamics, biogeochemical processes, and microorganism adaptations in sea ice environments.

Geckos are famous for the skill of switchable adhesion that they use to stick on various surface while keep their fingers super clean. In the dissertation, a unique mechanism was discovered to explain gecko self-cleaning phenomena. Using atomic force microscopy (AFM), we managed to compare the microparticle-substrate adhesion and the microparticle-seta adhesion with a single seta bonded to the AFM cantilever. A dynamic effect was approved that high pulling-off speed could increase the microparticle-substrate adhesion and thus the self-cleaning appears at high moving speed. Based on the self-cleaning theory, a gecko-inspired N-doped graphene surface with switchable adhesion was achieved, which was designed into a bio-inspired micromanipulator with a success rate over 90%. When electrical bias was applied on this biomimetic surface, the charge concentration induced an electrical double layer (ELD) on the convex surfaces, which attracts polar water molecules to form a water bridge on it, significantly enhancing the adhesion on the wrinkled graphene surface, mimicking the capillary force on beetle feet. Therefore, the bio-inspired adhesive surface can be controlled with speed, electrical bias, humidity and different material surfaces. The water attraction phenomenon on the polarized surface was further tested for the potential application of water collection and evaporation in microsystems.

Les méthodes actuelles pour détecter et identifier des microorganismes dans un échantillon sont lentes et complexes. Les techniques d'identification bactérienne, par exemple, nécessitent généralement une étape de culture bactérienne, introduisant des délais pouvant dépasser les 48 heures. Dans plusieurs domaines, telles la recherche arctique, la santé et l'industrie agroalimentaire, la lenteur des analyses bactériologiques peut avoir de lourdes conséquences humaines ou financières. Il existe donc un réel intérêt pour la conception de capteurs sensibles permettant d'outrepasser l'étape de culture bactérienne. Par le passé, notre groupe de recherche a développé une technique de biodétection basée sur les modes de galerie de multiples microsphères fluorescentes en suspension libre dans un échantillon. La sensibilité et la robustesse de cette approche permettent d'envisager son intégration dans un biocapteur rapide et portatif. Cependant, la technologie n'est pas assez mature sous sa forme actuelle pour permettre cette intégration. L'objectif de nos travaux de recherche était donc d'intégrer notre technologie dans un système de laboratoire efficace. Pour ce faire, une nouvelle instrumentation optofluidique est proposée. Cette dernière joint un microscope à fluorescence et un système microfluidique conçu pour mélanger une solution de microsphères avec un échantillon contenant des bactéries. Le mélange est réalisé par un micromélangeur utilisant des rainures dont l'orientation et la position sont optimisées pour favoriser la dispersion de particules solides en suspension dans un fluide. Différentes méthodes d'apprentissage machine servant à analyser les modes de galerie de microsphères fluorescentes sont également décrites. En termes de rapidité, ces dernières surpassent de loin l'algorithme IMARI originellement proposé par notre groupe. Au final, l'instrumentation optofluidique et les méthodes d'analyses présentées dans ce mémoire ont permis de détecter la présence de deux types de picocyanobactéries nordiques. Les avancées réalisées pendant la maîtrise confirment donc le potentiel de notre approche et son intégration éventuelle dans un capteur portatif. / The detection and the identification of microorganisms in a liquid sample is, more often than not, a slow and complex process. The current bacterial identification methodologies, for instance, typically require bacterial growth on culture media, a step which introduces delays of 48 hours or more. In fields such as arctic research, healthcare or food production, these delays can beget serious human and financial consequences. Thus, there is a growing interest for sensitive biosensors capable of bypassing the bacterial growth step. Our research group as previously presented a biodetection scheme based on the analysis of the whispering gallery modes of multiple fluorescent microspheres free-floating in the solution under test. The sensitivity and the robustness of this approach promote its eventual use in a fast and portable biosensing device. However, under its current form, our technology still lacks the appropiate maturity to be integrated in such a device. The research presented in this thesis thus aimed at integrating our technology in an effective laboratory system. To that end, an improved optofluidic instrumentation is proposed. It joins a fluorescent microscope to a microfluidic chip capabe of mixing a solution of microspheres with a sample containing bacteria. The mixing if achived via a staggered herringbone mixer with a groove orientation optimized to promote the dispersion of solide microparticles in suspension. Several machine learning algorithms are also proposed to analyse the whispering gallery modes of our free-floating fluorescent microspheres. In terms of analysis speed, these methods outperform, by a great margin, the IMARI algorithm previously proposed by our group. In the end, the proposed instrumentation and algorithms were used to sucessfully detect the presence of two types of arctic picocyanobacteria. The contributions presented in this thesis thus confirm the potential of our biodetection scheme and further pave the way towards portable biosensors.

Dans presque tous les environnements, les microorganismes cohabitent avec d'autres microorganismes. Cette coexistence donne lieu à des interactions qui peuvent jouer un rôle crucial dans l'altération et la préservation des produits laitiers. Cependant, ces interactions microbiennes et leurs rôles dans la détérioration des produits laitiers restent mal connus. De plus, le manque de méthodes expérimentales à haut débit limite notre capacité à explorer les interactions microbiennes pour des applications alimentaires. L'objectif de ces travaux était de développer de nouvelles approches systémiques pour caractériser des cultures d'intérêt laitier ainsi que leurs interactions écologiques et fonctionnelles. Pour ce faire, des méthodes à haut débit ont été développées à l'aide d'une plateforme automatisée et de l'analyse d'image pour cartographier les interactions microbiennes de l'environnement laitier. Les résultats de ces travaux ont démontré que les approches de culture à haut débit sont robustes pour quantifier les interactions microbiennes écologiques et fonctionnelles. Il a été montré que les interactions microbiennes pouvaient engendrer de la résilience chez les bactéries lactiques face au stress. À grande échelle, et dans un contexte de diversité microbienne élevée, il a été démontré que les interactions microbiennes dépendent largement des souches et ne peuvent être généralisées. Un total de 1142 interactions bidirectionnelles entre des microorganismes de l'environnement laitier a été cartographié. La directionnalité, la force et les types d'interactions écologiques variaient en fonction de l'origine d'isolement des souches. Tandis que la coopération prédominait parmi les microorganismes isolés du fromage, l'exploitation demeurait le type d'interaction privilégié chez les microorganismes issus du lait cru. Les souches coopérantes avaient, en moyenne, des comportements écologiques plus similaires que les souches concurrentes, ce qui suggère l'existence de cliques microbiennes. De plus, certaines souches ayant la capacité d'influencer la croissance globale de la communauté microbienne ont été identifiées. Par ailleurs, un nouveau phénotype d'interaction a été rapporté pour la première fois entre Pseudomonas aeruginosa AN63 et Lactococcus cremoris ATCC 19257, cette dernière produisant un pigment rose rouge lorsqu'elle est en interaction avec Pseudomonas aeruginosa AN63. De manière globale, ces résultats offrent un portrait inédit des relations sociales entre les microorganismes de l'environnement laitier. Le jumelage des profils écologiques et fonctionnels apporte une nouvelle perspective au criblage des cultures d'intérêt pour les produits laitiers. La méthode développée et le jeu de données attenant ouvrent de nouvelles perspectives sur l'identification de combinaisons de souches ayant des comportements souhaitables pour diverses applications et d'éviter celles qui pourraient entraîner des problèmes de qualité. Par exemple, des consortiums de cultures bio-protectrices capables de prolonger naturellement la durée de conservation des produits laitiers pourraient être développés. À long terme, les résultats de cette étude pourraient contribuer à la réduction du gaspillage alimentaire. / In almost all environments, microorganisms coexist with other microorganisms. This coexistence leads to interactions that can play a crucial role in both the spoilage and preservation of dairy products. However, these microbial interactions and their roles in the deterioration of dairy products remain poorly understood. Furthermore, the lack of high-throughput experimental methods limits our ability to explore microbial interactions for food applications. The objective of this study was to develop new systemic approaches to characterize dairy-related cultures, as well as their ecological and functional interactions. To achieve this, high-throughput methods were developed using an automated platform and image analysis to map microbial interactions in the dairy environment. The results of this work demonstrated that high-throughput culturing approaches are robust for quantifying ecological and functional microbial interactions. It was shown that microbial interactions can confer resilience to lactic acid bacteria under stress. On a large scale, and in a context of high microbial diversity, microbial interactions were found to be largely strain-dependent and cannot be generalized. A total of 1142 bidirectional interactions between microorganisms from the dairy environment were mapped. The directionality, strength, and types of ecological interactions varied depending on the strains' isolation sources. While cooperation predominated among microorganisms isolated from cheese, exploitation remained the preferred type of interaction for microorganisms from raw milk. Cooperative strains exhibited, on average, more similar ecological behaviors than competitive strains, suggesting the existence of microbial cliques. Additionally, some strains capable of influencing the overall growth of the microbial community were identified. Furthermore, a new interaction phenotype was reported for the first time between Pseudomonas aeruginosa AN63 and Lactococcus cremoris ATCC 19257, the latter producing a red-pink pigment when interacting with Pseudomonas aeruginosa AN63. Overall, these results provide a novel perspective on the social relationships between microorganisms in the dairy environment. The developed method and the accompanying dataset open new avenues for identifying combinations of strains with desirable behaviors for various applications, while avoiding those that could lead to quality issues. For instance, bio-protective culture consortia capable of naturally extending the shelf life of dairy products could be developed. In the long term, the findings of this study could contribute to reducing food waste.