Cardiovascular diseases (CVD) remain one of the leading causes of deaths worldwide. The formation and presence of aneurysm is a very important question in the study of this CVDs. An aneurysm is a balloon-like bulge on a blood vessel which forms over time. An aneurysm is usually considered to be a result of weakening of the blood vessel walls, this definition has stood over many years without being conclusively proven. Eventually, the aneurysm could clot or burst due to degradation of the aneurysm wall and accumulation of blood. The latter would lead to internal bleeding and result in a stroke. Local hemodynamics have been found to be very important in the study of the evolution of an aneurysm. In this study, a steady flow experimental investigation was conducted using planar Particle Image Velocimetery (PIV) on a rigid flow phantom of an idealised geometry consisting of a curve parent artery and a spherical aneurysm located on the outer convex side of the curvature. The flow phantom was fabricated directly using a commercially available desktop Stereolithography (STL) 3D printer instead of the more conventional investment casting method using a core. Although 3D printing technologies have been around for many years, the fabrication of flow phantoms by direct printing is still largely under-explored. This thesis details the results of investigation into the optimal printing and post-printing procedures required to produce a flow phantom of suitable clarity and transparency. Other important areas of concern such as the geometric accuracy, surface topography and refractive index of the final model are also investigated. A planar PIV is conducted to study the impact of flow rates on the local flow field in and around the aneurysm and their impact on the wall shear stress. It was found that direct 3D printing is appropriate for the fabrication of flow phantoms suitable for PIV or other flow visualisation techniques. It reduces the complexities and time needed compared to the conventional investment casting methods. It was observed that the optical properties of the printed material such as the high refractive index (RI) and the transmittivity of light could cause a problem in large models. From the PIV measurements it was found that flow rates affect the flow field in both the parent artery and the aneurysm. First, high velocities were observed on the outer curvature of the parent artery. Secondly the centre of rotation in the aneurysm is not at the geometric centre but is displaced slightly in the direction of the flow. Finally, the flow rate affects the angle in which flow enters the aneurysm from the parent vessel. This change in the flow angle affects the flow within the aneurysm. A higher flow rate in the parent artery increases the incident angle which brings the centre of rotation closer to the geometric centre of the aneurysm, this changes the location and magnitude of high velocities and hence the local wall shear stress (WSS) on the wall of the aneurysm. This may have implications in the evolution of aneurysms. / Mechanical and Industrial Engineering

Ce travail a pour objet d’améliorer les performances d’un réacteur photocatalytique tubulaire de traitement des COVs, en le garnissant avec des supports structurés et imprégnés de TiO2. Grâce à un montage adapté, l’efficacité du réacteur est suivie en mesurant le taux de conversion du méthanol, choisi comme polluant modèle. Différentes géométries de support catalytique ont été fabriquées par stéréolithographie. Parmi toutes les géométries testées, la structure alvéolaire, constituée de canaux verticaux pour le passage du fluide et de canaux horizontaux pour le passage de la lumière, permet une efficacité optimale du réacteur. La modélisation du réacteur, tenant compte de la distribution de la lumière dans le support, montre que le transfert de matière est limitant lorsque le diamètre des canaux est plus petit que 4 mm. En revanche, lorsque le diamètre des canaux est supérieur à 5 mm, le manque d'efficacité est dû à une diminution de l'absorption de la lumière incidente. / The aim of the work is to improve the efficiency of a photocatalytic tubular reactor for VOCs abatement, while loading it with structured catalytic supports impregnated of TiO2.Thanks to a photocatalytic set-up , the efficiency of the reactor is followed by measuring the conversion rate of a model pollutant: methanol. Different geometries of support have been made by stereolithography. Among all tested geometries, the alveolar structure, composed of vertical channels for light penetration, and horizontal channels for the circulation of the gas flow, leads to an optimal degradation of the pollutant. The modelling of the reactor, taking into account the light distribution, shows that the mass transfer is limiting when the diameter of the channels is smaller than 4 mm. On the other hand, when the diameter of the channels is bigger than 5 mm, the lack of efficiency is due to a reduction of the absorption of the incident light by the catalytic surface.

<p>Additive manufacturing (AM) can be an advantageous substitute to various traditional manufacturing techniques. Due to the ability to rapidly create products, AM has been traditionally used to prototype more efficiently. As the industry has progressed, however, use cases have gone beyond prototyping into production of complex parts with unique geometries. Amongst the most popular of AM processes is fused deposition modeling (FDM). FDM fabricates products through an extrusion technique where plastic filament is heated to the glass transition temperature and extruded layer by layer onto a build platform to construct the desired part. The purpose of this research is to elaborate on the potential of this technology, while considering environmental impact as it becomes more widespread throughout industry, research, and academia.</p> <p>Although AM consumes resources more conservatively than traditional methodologies, it is not free from having environmental impacts. Several studies have shown that additive manufacturing can affect human and environmental health by emitting particles of a dynamic size range into the surrounding environment during a print. To begin this study, chapters investigate emission profiles and characterization of emissions from FDM 3D printers with the intention of developing a better understanding of the impact from such devices. Background work is done to confirm the occurrence of particle emission from FDM using acrylonitrile butadiene styrene (ABS) plastic filament. An aluminum bodied 3D printer is enclosed in a chamber and placed in a Class 1 cleanroom where measurements are conducted using high temporal resolution electrical low-pressure impactor (ELPI), scanning mobility particle sizer (SMPS), and optical particle sizer (OPS), which combined measure particles of a size range 6-500nm. Tests were done using the NIST standard test part and a honeycomb infill cube. Results from this study show that particle emissions are closely related to filament residence time in the extruder while less related to extruding speed. An initial spike of particle concentration is observed immediately after printing, which is likely a result of the long time required to heat the extruder and bed to the desired temperature. Upon conclusion of this study, it is theorized that particles may be formed through vapor condensation and coagulation after being released into the surrounding environment.</p> <p>With confirmation of FDM ultrafine particle emission at notable concentrations, an effort was consequently placed on diagnosing the primary cause of emission and energy consumption based on developed hypotheses. Experimental data suggests that particle emission is mainly the result of condensing and agglomerating semi-volatile organic compounds. The initial emission spike occurs when there is dripping of semi-liquid filament from the heated nozzle and/or residue left in the nozzle between prints; this supports the previously stated hypothesis regarding residence time. However, the study shows that while printing speed and material flow influence particle emission rate, the effects from these factors are relatively insignificant. Power profile analysis indicates that print bed heating and component temperature maintaining are the leading contributors to energy consumption for FDM printers, making time the primary variable driving energy input.</p> <p>To better understand the severity of FDM emissions, further investigation is necessary to diligence the makeup of the process output flows. By collecting exhaust discharge from a Makerbot Replicator 2x printing ABS filament and diffusing it through a type 1 water solution, we are able to investigate the chemical makeup of these compounds. Additional exploration is done by performing a filament wash to investigate emissions that may already be present before extrusion. Using solid phase micro-extraction, contaminants are studied using gas chromatography mass spectrometry (GCMS) thermal desorption. Characterization of the collected emission offers more comprehensive knowledge of the environmental and human health impacts of this AM process.</p> <p>Classification of the environmental performance of various manufacturing technologies can be achieved by analyzing their input and output material, as well as energy flows. The unit process life cycle inventory (UPLCI) is a proficient approach to developing reusable models capable of calculating these flows. The UPLCI models can be connected to estimate the total material and energy consumption of, and emissions from, product manufacturing based on a process plan. The final chapter focuses on using the knowledge gained from this work in developing UPLCI model methodology for FDM, and applying it further to the second most widely used AM process: stereolithography (SLA). The model created for the FDM study considers material input/output flows from ABS plastic filament. Energy input/output flows come from the running printer, step motors, heated build plate, and heated extruder. SLA also fabricates parts layer by layer, but by the use of a photosensitive liquid resin which solidifies when cured under the exposure of ultraviolet light. Model material input/output flows are sourced from the photosensitive liquid resin, while energy input/output flows are generated from (i) the projector used as the ultraviolet light source and (ii) the step motors. As shown in this work, energy flow is mostly time dependent; material flows, on the other hand, rely more on the nature of the fabrication process. While a focus on FDM is asserted throughout this study, the developed UPLCI models show how conclusions drawn from this work can be applied to different forms of AM processes in future work.</p>

Cardiovascular diseases (CVDs) are a leading cause of death worldwide, emphasizing the need for advanced and effective intervention and treatment measures. Hypertension, a significant risk factor for CVDs, is characterized by reduced vascular compliance in arterial vessels. There is a significant rise in interest in exploring the viscoelastic properties of arteries in the last few years, for the treatment of these diseases. This study aims to develop an experimental setup using 3D Printing Technology to test viscoelastic arterial models for the validation of a diagnostic device for cardiovascular diseases. The research investigates the selection of polymer-based materials that closely mimic the viscoelastic properties of arterial vessels. An experimental setup is designed and fabricated to perform mechanical tests on 3D-printed specimens. The study utilizes a mathematical model to describe the viscoelastic behavior of the materials. The model's predictions are validated using experimental data obtained from the mechanical tests. This study demonstrates the potential of 3D printing technology in fabricating specimens using elastic and flexible resin materials. These specimens closely replicate the mechanical properties of native arteries, offering a tangible platform for controlled mechanical testing. Stress relaxation tests on the3D printed specimens highlight the viscoelastic properties of fabricated materials, shedding light on their behavior under strain. The study goes further to model the mechanics of these materials, utilizing the Fractional Voigt model to capture the intricate balance between elastic and resistive behaviors under varying deformation levels. The results highlight the successful fitting of the Fractional Voigt model to the experimental data, confirming the viscoelastic behavior of the specimens. The obtained values of α and RMSE indicate a good representation of arterial mechanical properties within the viscoelastic arterial model, under different loading conditions. This research contributes to improving cardiovascular device validation and offers a practical and reliable alternative to invasive experiments. Future works include exploring different materials and conditions for arterial modeling and enhancing the precision and scope of the viscoelastic model. Overall, this study advances the understanding of cardiovascular biomechanics, contributing to the development of more effective diagnostic devices for cardiovascular diseases.

Yes / Three-dimensional printing (3DP) has demonstrated great potential for multi-material fabrication because of its capability for printing bespoke and spatially separated material conformations. Such a concept could revolutionise the pharmaceutical industry, enabling the production of personalised, multi-layered drug products on demand. Here, we developed a novel stereolithographic (SLA) 3D printing method that, for the first time, can be used to fabricate multi-layer constructs (polypills) with variable drug content and/or shape. Using this technique, six drugs, including paracetamol, cffeine, naproxen, chloramphenicol, prednisolone and aspirin, were printed with dfferent geometries and material compositions. Drug distribution was visualised using Raman microscopy, which showed that whilst separate layers were successfully printed, several of the drugs diffused across the layers depending on their amorphous or crystalline phase. The printed constructs demonstrated excellent physical properties and the different material inclusions enabled distinct drug release profiles of the six actives within dissolution tests. For the first time, this paper demonstrates the feasibility of SLA printing as an innovative platform for multi-drug therapy production, facilitating a new era of personalised polypills.

Les phosphates de calcium tels que le β-TCP sont utilisés depuis des décennies comme substitut osseux synthétique. Leurs bonnes propriétés chimiques et leur comportement analogue au tissu osseux in vivo et in vitro peuvent être améliorés par la technique de mise en forme employée. Il est aujourd'hui largement admis qu'une architecture poreuse optimisée aura un impact positif sur la bioactivité du matériau. Cette étude vise à étudier les liens existant entre une structure macroporeuse en β-TCP et la prolifération et différenciation cellulaire. Le β-TCP est fabriqué par précipitation aqueuse. Les paramètres de synthèse sont optimisés afin d'avoir un produit répondant aux normes ISO 13175 et 13779. Trois méthodes de mise en forme ont été choisies pour leur aptitude à générer une macroporosité originale. L'imprégnation d'une structure polymérique par une suspension génère un réseau de pores sphériques (PS), la stéréolithographie génère des pores cubiques interconnectés (3D) et la congélation orientée produit un réseau de pores tubulaires ellipsoïdaux parallèles au sens de la congélation (CO). Deux tendances émergent des cultures de cellules souches mésenchymateuses humaines: PS et 3D favorisent la prolifération alors que CO favorise la pénétration cellulaire et l'activité de la phosphatase alcaline. Cette dernière est favorisée par le β-TCP et cette aptitude est améliorée par la congélation orientée. Cela pourrait s'expliquer par l'état d'avancement de la différenciation cellulaire: les cellules sur les échantillons CO semblent être à un stade de différenciation plus avancé. Des essais complémentaires sur l'expression de gènes clés sont en cours pour vérifier cette hypothèse. / Calcium phosphates such as β-TCP have been used for decades as synthetic bone substitutes. Its good chemical properties and its similar behavior to that of the bone in vivo and in vitro can be enhanced by the chosen shaping method. It is nowadays largely accepted that an optimized porous architecture will have a positive impact on the material's bioactivity. This study aims at studying the links between a porous architecture and cell proliferation and differentiation. β-TCP was manufactured by aqueous precipitation. Synthesis parameters were optimized in order to get a product complying with ISO 13779 and 13175 requirements. Three shaping methods were chosen for their ability to generate original structures. The impregnation of a polymeric scaffold yields a network of interconnected spherical pores (PS), stereolithography yields a network of interconnected cubical pores (3D) and ice templating yields a network of parallel ellipsoidal channel-like structure (CO). Two different trends emerged from the human mesenchymal stem cell culture: PS and 3D favored cell proliferation whereas CO promoted cell penetration and alkaline phosphatase activity. The latter is stimulated by β-TCP and this ability is enhanced by freeze casting. This could be explained by the state of cell differentiation: cells on CO samples seem to be far more differentiated than the other ones. However the study of key genes expression is needed to confirm this hypothesis.

La stéréolithographie biphotonique (TPS) est une technique de microfabrication 3D basée sur la polymérisation par absorption biphotonique qui permet d’obtenir en une seule étape des structures 3D complexes avec des détails sub-100nm. Aujourd’hui, en raison des conditions spécifiques de fabrication liées à la TPS (fort flux, confinement spatial de la photoréaction,…), un des enjeux concerne le développement de matériaux fonctionnels compatibles avec ce procédé. Dans ce contexte, l’objectif de cette thèse a été de développer de nouveaux matériaux fonctionnels à base de polymères à empreintes moléculaires (MIP) pour élaborer des capteurs chimiques. Une première partie de ce travail a consisté à mettre en place différentes méthodes dédiées à la caractérisation des propriétés géométriques, chimiques et mécaniques des matériaux élaborés par TPS. Par exemple, la vibrométrie laser a été utilisée pour la première fois afin de sonder de façon non-invasive les propriétés mécaniques de microstructures réalisées par TPS. Dans un second temps, ce travail a été mis à profit pour étudier l’impact du processus de fabrication (i.e. conditions photoniques) ainsi que des paramètres physico-chimiques affectant la photoréaction (i.e. inhibition par oxygène et nature du monomère) sur les propriétés finales des matériaux. Enfin, en s’appuyant sur les résultats obtenus, des microcapteurs chimiques à base de MIP, à lecture optique ou mécanique, ont été fabriqués. Leurs propriétés de reconnaissance moléculaire, ainsi que leurs sélectivités ont été démontrées pour une molécule cible modèle (D-L-Phe). / The two-photon stereolithography (TPS) technique is a micro-nanofabrication method based on photopolymerization by two-photon absorption that allows in a single manufacturing step to obtain complex 3D structures with high-resolution details (sub-100nm). Due to the specific conditions of TPS process (intense photon flux, spatial confinement of the photoreaction…) one of the main concerns today is the development of functional materials compatible with the TPS. According to the aforementioned, the general objective of this thesis was to develop new functional materials based on molecularly imprinted polymers (MIP) to elaborate chemical microsensors. In the first step of this work, different methods were implemented to characterize the geometrical, chemical and mechanical properties of the materials synthesized by TPS. For example, laser-Doppler vibrometry was used for first time to evaluate the mechanical properties of microstructures fabricated by TPS in a non-invasive way. In the second step, the characterization methodology was used to study the impact of the manufacturing process (i.e. photonic conditions) and the physicochemical parameters that affect the photoreaction (i.e. oxygen inhibition and the nature of the monomer) and the final properties of the materials. Finally, the obtained results enabled the prototyping of chemical microsensors based on MIP. Their molecular recognition properties and their selectivity were demonstrated for the molecule (D-L-Phe) by an optical and a mechanical sensing method.

Abstract An experimental method was developed that demonstrated the size effects in forming thin sheet metals, and a finite element model was developed to predict the effects demonstrated by the experiment. A universal testing machine (UTM) was used to form aluminum and copper of varying thicknesses (less than 1mm) into a hemispherical dome. A stereolithography additive manufacturing technology was used to fabricate the punch and die from a UV curing resin. There was agreement between the experimental and numerical models. The results showed that geometric size effects were significant for both materials, and these effects increased as the thickness of the sheets decreased. The demonstration presents an inexpensive method of testing small-scale size effects in forming processes, which can be altered easily to produce different shapes and clearances.

Background: Single ventricle congenital heart defects with cyanotic mixing between systemic and pulmonary circulations afflict 2 per 1000 live births. Following the atriopulmonary connection proposed by Fontan and Baudet in 1971, the present procedure is the total cavopulmonary connection (TCPC), where the superior vena cava (SVC) and inferior vena cava (IVC) are sutured to the left pulmonary artery (LPA) and right pulmonary artery (RPA). However, surgeon preference dictates the implementation of the extra-cardiac and intra-atrial varieties of the TCPC. Overall efficiency and hemodynamic advantage of the competing methodologies have not been determined. Hypothesis: It is hypothesized that an understanding of the experimental fluid dynamic differences between various Fontan surgical methodologies in the TCPC allows for power loss evaluation toward improved surgical planning and design. Methods: Toward such analysis, a previously developed data processing methodology is applied to create an anatomic database of single ventricle patients from in vivo magnetic resonance imaging (MRI) to examine the gamut of TCPC anatomies. From stereolithographic models of representative cases, pressure and flow data are used to quantify control volume power loss to measure overall efficiency. particle image velocimetry (PIV) is employed to detail flow structures in the vasculature. Results are validated with dye injection flow visualization and 3-D phase contrast magnetic resonance imaging (PC-MRI) velocimetry, highlighting flow phenomena that cannot be captured with in vivo MRI due to prohibitively long scanning times. Preliminary results illustrate the variation of control volume power loss over several TCPC anatomies with varying flow conditions, the application of PIV, and validation approaches with 3-D PC-MRI velocimetry. Data from control volume power loss evaluation demonstrate a correlation with TCPC anatomy, providing added clinical knowledge of optimal TCPC design. Findings from PIV and 3-D PC-MRI velocimetry reveal a means for quantitatively comparing flow structure. Dye injection flow visualization offers qualitative insight into limitations of the selected velocimetry techniques.

No description available.