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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
711

SMART CAPSULE WITH STIMULI-RESPONSIVE POLYMERS FOR TARGETED SAMPLING FROM THE GASTROINTESTINAL TRACT

Sina Nejati (17029686) 25 September 2023 (has links)
<p dir="ltr">The gastrointestinal (GI) tract and its diverse microbial community play a significant role in overall health, impacting various aspects such as metabolism, physiology, nutrition, and immune function. Disruptions in the gut microbiota have been associated with metabolic diseases, colorectal cancer, diabetes, obesity, inflammatory bowel disease, Alzheimer's disease, and depression. Despite recognizing the importance of the gut microbiota, the interrelationship between microbiota, diet, and disease prevention remains unclear. Current techniques for monitoring the microbiome often rely on fecal samples or invasive endoscopic procedures, limiting the understanding of spatial variations in the gut microbiota and posing invasiveness challenges. To address these limitations, this dissertation focuses on the design and development of an electronic-free smart capsule platform capable of targeted sampling of GI fluid within specific regions of the GI tract. The capsule can be retrieved for subsequent bacterial culture and sequencing analysis. The capsule design is based on stimuli-responsive polymers and superabsorbent hydrogels, chosen for their proven safety, compatibility, and scalability. By leveraging the pH variation across the GI tract, the pH-sensitive polymeric coatings dissolve at the desired region, activating the sampling process. The superabsorbent hydrogel inside the capsule collects the sampled GI fluid and facilitates capsule closure upon completion of sampling. Systematic studies were conducted to identify suitable pH-responsive polymer coatings, superabsorbent hydrogels, and processing conditions that effectively operated within the physiological conditions of the GI tract. The technology's effectiveness and safety were validated through rigorous <i>in vitro</i> and <i>in vivo</i> studies using pig models. These studies demonstrated the potential of the technology for targeted sampling of GI fluid in both small and large intestinal regions, enabling subsequent bacterial culture and gene sequencing analysis. Additionally, the capsule design was enhanced with the integration of a metal tracer, enabling traceability throughout the GI tract using X-ray imaging and portable metal detectors for ambulatory screening. This technology holds promise as a non-invasive tool for studying real-time metabolic and molecular interactions among the host, diet, and microbiota in challenging-to-access GI regions. Its application in clinical studies can provide new insights into diet-host-microbiome interactions and contribute to addressing the burden faced by patients and their families dealing with GI-related diseases.</p>
712

Development and 3D Printing of Intrinsically Stretchable Materials for Microsupercapacitors

Engman, Alexander January 2020 (has links)
The purpose of this thesis is to develop a simple Direct Ink Writing (DIW) method for fabricating intrinsically stretchable microsupercapacitors as ef- fective on-chip energy storage devices for the emerging stretchable electron- ics. Using the printing method for fabricating intrinsically stretchable elec- tronic components remains a novel approach. In this thesis, interdigitated structures of intrinsically stretchable electrodes were printed on a stretchable thermoplastic polyurethane (TPU) substrate using a formulated ink based on Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate. Formulated elec- trolytes based on Poly(4-styrene Sulfonic Acid) and Phosphoric Acid were applied to the electrodes to complete the fabrication of microsupercapacitors. Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Elec- trochemical Impedance Spectroscopy (EIS) were used to characterize the per- formance of the devices. The stretchability of the electrodes was also mea- sured. Results from CV-measurements revealed a maximum capacitance of740 µF cm−2 at a scan rate of 5 mV s−1. GCD-measurements showed a capaci- tance of 952 µF cm−2 for the same device and an equivalent series resistance of approximately 7 kΩ. The printed electrodes exhibited a stretchability of 80%. The results show the feasibility of fabricating intrinsically stretchable energystorage devices using commercially available materials and a simple 3D print- ing technique. This method could be used as a high-throughput and low-cost method for stretchable electronics applications. / Syftet med detta arbete är att utveckla en simpel Direct Ink Writing (DIW) metod för framställning av intrinsiskt sträckbara mikrosuperkondensatorer som effektiva on-chip energilagrinsenheter i kommande sträckbar elektronik. Användandet av DIW för att tillverka intrinsiskt sträckbara elektroniska kom- ponenter är ett nytt tillvägagångssätt. I detta arbete trycktes interdigiterade strukturer av intrinsiskt sträckbara elektroder på ett sträckbart termoplastiskt polyuretan (TPU) substrat genom att använda ett formulerat bläck baserat på Poly(3,4-etylendioxitiofen):Polystyren Sulfonat (PEDOT:PSS). Formuler- ade elektrolyter baserade på Poly(4-styrensulfonsyra) och Fosforsyra applicer- ades på elektroderna för att färdigställa tillverkningen av mikrosuperkonden- satorer. Cyklisk Voltammetri (CV), Galvanostatisk uppladdning-urladdning (eng. GCD) och Elektrokemisk Impedansspektroskopi (EIS) användes för att karaktärisera enheternas prestanda. Bläckets sträckbarhet uppmättes också. Resultaten från CV-mätningar visade att den maximala kapacitansen var 742µF cm−2 vid skanningsfrekvensen 5 mV s−1. Kapacitansen från GCD-mätningar var 952 µF cm−2 för samma enhet och den ekvivalenta serieresistansen var cirka 7 kΩ. Sträckbarheten som de tryckta elektroderna uppvisade var 80%. . Re- sultaten påvisar möjligheten att kunna framställa intrinsiskt sträckbara en-ergilagringsenheter genom att använda kommersiellt tillgängliga material och en simpel metod för friformsframställning. Denna metod skulle kunna använ- das för att framställa sträckbara elektroniska komponenter till låg kostnad och med hög produktionstakt.
713

Anisotropy Evolution Due to Surface Treatment on 3D-Printed Fused Deposition Modeling (FDM) of Acrylonitrile Butadiene Styrene (ABS)

Lozinski, Blake E 01 January 2017 (has links)
Purpose: This paper will present insight to the methodology and results of the experimental characterization of Acrylonitrile Butadiene Styrene (ABS) using Fused Deposition Modeling (FDM). The work in this research explored the effects of print orientation, surface treatment, and ultraviolet (UV) light degradation with the utilization of Digital Image Correlation (DIC) on ABS tensile specimens. Design/methodology: ABS specimens were printed at three build orientations (flat (0 degrees), 45 degrees, and up-right (90 degrees)). Each of these specimens were treated with three different surface treatments including a control (acrylic paint, Cyanoacrylate, and Diglycidyl Bisphenol A) followed by exposure to UV light to the respective batches. This experiment design will provide tensile direction properties with the effect of thermoset coatings and UV degradation. Dogbone FDM specimens based on ASTM standard D638 type IV were printed on a Stratasys Dimension SST (Soluble Support Technology) 1200es 3D Printer and loaded into a MTS Landmark Servohydraulic Test Systems. Analysis was preformed on the fracture section of the tensile specimens utilized DIC and comparing Ultimate Tensile Strength (UTS) and Ultimate Fracture Strength (UFS). Findings: From the results UV light did not play a large factor in the strength of the specimens. The print orientation showed the largest anisotropic behavior where some specimens experienced as much as a 54% difference in ultimate tensile strength. Thermoset coated specimens experienced a maximum of 2% increase in strength for the Cyanoacrylate and Diglycidyl Bisphenol A specimens where the acrylic paint and natural did not. Several findings were of value when looking at the stress strain plots. Originality/value: This paper provides knowledge to the limited work on print build orientation, thermoset coatings and, UV light on ABS specimens. Very little to no work has been done on these three properties. This paper can serve as the foundation of future work on external applications on ABS plastics.
714

RELATING MICROSTRUCTURE TO PROCESS VARIABLES IN BEAM-BASED ADDITIVE MANUFACTURING OF INCONEL 718

Thompson, John Ryan 04 June 2014 (has links)
No description available.
715

Resilience and Toughness Behavior of 3D-Printed Polymer Lattice Structures: Testing and Modeling

Al Rifaie, Mohammed Jamal 21 August 2017 (has links)
No description available.
716

Feasibility of Attaining Fully Equiaxed Microstructure through Process Variable Control for Additive Manufacturing of Ti-6Al-4V

Kuntz, Sarah Louise 01 June 2016 (has links)
No description available.
717

Automation of Fused Filament Fabrication : Realizing Small Batch Rapid Production / Automatisering av Fused Filament Fabrication : Ett sätt att förverkliga snabb småserietillverkning

ANDERSSON, AXEL January 2021 (has links)
In this bachelor thesis, I examine how automation of fused filament fabrication (FFF) can be implemented, and what the limitations are for different kinds of automation solutions for FFF. Fused filament fabrication is a 3D-printing technology where a material is extruded through a nozzle, layer by layer, to create a print. The thesis also provides a calculation for the commercial feasibility of small batch rapid production with the implementation of an automation solution for FFF. The approach was a qualitative study containing five interviews, combined with empirical knowledge and data from the additive manufacturing company Svensson 3D. This was complemented with an analysis of which criteria to use when evaluating FFF automation solutions, and a framework for looking at FFF from an operator perspective. To calculate commercial feasibility of automation solutions for FFF, Internal Rate of Return and Payback Time were used. This resulted in six criteria to evaluate solutions for automation of FFF, three evaluations of problems within three solutions for automation of FFF, and a finding showing that small batch rapid production is commercially feasible with automated FFF. Lastly, the thesis contains a discussion regarding what the future is for FFF, and the limitations of the framework presented for evaluating automated FFF systems. Possible promising solutions for automated FFF are presented, together with ideas for how design for additive manufacturing can help shape the future of automated FFF. / I det här kandidatarbetet undersöker jag hur automatisering inom fused filament fabrication (FFF) kan implementeras, och vad begränsningarna är för olika sorters automatiseringslösningar för FFF. Det läggs även fram en uträkning för den kommersiella gångbarheten för small batch rapid production med implementeringen av ett automatiskt FFF-system. Tillvägagångsättet bestod av en kvalitativ studie baserad på fem intervjuer, kombinerad med empirisk kunskap och data från additiva tillverkningsföretaget Svensson 3D. Det här kompletterades med en analys av vilka parametrar som bör användas för att utvärdera lösningar för FFF-automatisering, och ett ramverk där automatiseringslösningarna betraktas ur ett operatörs-perspektiv. För att räkna ut den kommersiella gångbarheten för automatiseringslösningar av FFF användes internränta och återbetalningstid. Det här resulterade i sex parametrar för att utvärdera automatiseringslösningar för FFF, tre utvärderingar av vilka problem som finns i tre existerande automatiseringslösningar, och slutsatsen att small batch rapid production är kommersiellt gångbart för automatiserad FFF. Slutligen innehåller arbetet en diskussion gällande framtiden för FFF och begränsningarna hos det ramverk som presenterades för att utvärdera automatiserade FFF system. Möjliga lovande lösningar för automatiserad FFF presenteras och hur design för additiv tillverkning kan hjälpa till att forma framtiden för automatiserad FFF.
718

Prospects for Sustainable Micro-Factory Retailing in Canada: A Case Study of 3D Printed Electric Vehicles

Hachey, Stephen Quinn January 2018 (has links)
The contemporary global automotive industry has persisted, relatively unchanged, since its inception over a century ago. However, it appears that major changes may be underfoot with increasing environmental, social, and economic pressures to improve the industry's long-term sustainability. An alternative model, known as Micro-Factory Retailing (MFR), guided by the emerging field of Industrial Ecology (IE) has been proposed as a possible solution to the industry’s sustainability crisis. This thesis will explore the prospects of MFR in Canada and propose the use of 3D printed electric vehicles as a means to facilitate sustainable system innovation. To demonstrate the feasibility of this proposed technological pathway, three entrepreneurial firms attempting to disrupt the way in which cars are made, sold, and used will be studied. Although the timeline of such a major transition is currently unknown, Canada should act proactively to transition its role in the global automotive sector and lead the way towards a more sustainable automotive ecosystem through MFR. / Thesis / Master of Science (MSc)
719

Evaluation of different crosslinking methods in altering the properties of extrusion-printed chitosan-basedmulti-material hydrogel composites

Liu, Suihong, Zhang, Haiguang, Ahlfeld, Tilman, Kilian, David, Liu, Yakui, Gelinsky, Michael, Hu, Qingxi 30 May 2024 (has links)
Three-dimensional printing technologies exhibit tremendous potential in the advancing fields of tissue engineering and regenerative medicine due to the precise spatial control over depositing the biomaterial. Despite their widespread utilization and numerous advantages, the development of suitable novel biomaterials for extrusion-based 3D printing of scaffolds that support cell attachment, proliferation, and vascularization remains a challenge. Multi-material composite hydrogels present incredible potential in this field. Thus, in this work, a multi-material composite hydrogel with a promising formulation of chitosan/gelatin functionalized with egg white was developed, which provides good printability and shape fidelity. In addition, a series of comparative analyses of different crosslinking agents and processes based on tripolyphosphate (TPP), genipin (GP), and glutaraldehyde (GTA) were investigated and compared to select the ideal crosslinking strategy to enhance the physicochemical and biological properties of the fabricated scaffolds. All of the results indicate that the composite hydrogel and the resulting scaffolds utilizing TPP crosslinking have great potential in tissue engineering, especially for supporting neo-vessel growth into the scaffold and promoting angiogenesis within engineered tissues.
720

Modelo para el análisis del impacto de la manufactura aditiva en la gestión de la cadena de suministro

Núñez Rodríguez, Jairo 17 January 2022 (has links)
[ES] El desarrollo tecnológico, consecuencia de las revoluciones industriales, ha generado que constantemente en los procesos de manufactura se alteren y sustituyan las técnicas de producción, impactando, a su vez, la gestión de flujos de información, financieros y de materiales en las cadenas de suministro. La manufactura aditiva es considerada como una técnica de producción con alto potencial para impactar la configuración y gestión de las cadenas de suministro, dado que supone el aumento de la eficiencia y satisfacción de la demanda por medio de resultados personalizados, ajustados a las necesidades de los clientes, reduciendo tiempos y costos en el almacenamiento, transporte y empaque. Por estas razones, con la presente tesis doctoral se desarrolló un modelo matemático a través de la dinámica de sistemas que permitiera analizar el impacto en las cadenas de suministro que han apropiado el proceso de impresión 3d como uno de sus enfoques de producción. Se inició analizando el desarrollo de la manufactura aditiva (MA) a través del tiempo, para determinar las variables que describen los cambios, el estado de madurez y el nivel de penetración en los sectores económicos; para lograrlo, se realizaron revisiones de literatura y análisis bibliométrico. Posteriormente, se definió como unidad de análisis el sector salud, debido al grado de apropiación de la MA en los procesos de atención. Se realizó la caracterización del estado actual y la propuesta de escenarios que fueron analizados a partir del modelo que simulara el comportamiento de cada escenario. Para los escenarios aditivos se consideró el rol que desempeña el miembro de la cadena que implementa el proceso aditivo y cómo esto altera la estructura, los procesos de gestión y la relación entre los actores. Los resultados demuestran el alto potencial de impacto de la MA, desde los eslabones de producción hasta el acercamiento con el cliente, respecto a la literatura, está emergiendo la investigación respecto al desarrollo de granjas de impresión y estructuras atomizadas. Se describieron los procesos de gestión de la cadena y cómo el proceso aditivo permea en los roles, la dependencia y autonomía que tiene cada miembro; siendo las variables con mayor afectación los costos de producción y distribución, tiempos de espera, respuesta e intervenciones, así como los resultados satisfactorios. Se explica a través del contraste de tres escenarios, uno tradicional y dos aditivos la reducción de, al menos, el 50% del lead time de la cadena, 30% las cantidades de unidades de insumos y 20% la capacidad disponible. En contraste, todavía se evidencian grandes retos para una adecuada implementación, relacionados con el conocimiento, cobertura, poder de adquisición económica y el nivel de respuesta de la producción tradicional. Para futuras líneas de investigación, se señala la vinculación con las demás tecnologías de la industria 4.0, el análisis de cada uno de los procesos de gestión de la cadena y el desarrollo de modelos que permitan la selección de la estructura más apropiada para la inclusión de la MA a partir de simulación de escenarios aditivos, entre otros. / [CA] El desenvolupament tecnològic, conseqüència de les revolucions industrials, ha generat que constantment en els processos de manufactura s'alteren i substituïsquen les tècniques de producció, impactant, a la mateixa vegada, la gestió de fluxos d'informació, financers i de materials en les cadenes de subministrament. La manufactura additiva és considerada com una tècnica de producció amb alt potencial per a impactar la configuració i gestió de les cadenes de subministrament, atés que suposa l'augment de l'eficiència i satisfacció de la demanda per mitjà de resultats personalitzats ajustats a les necessitats dels clients, reduint temps i costos en l'emmagatzematge, transport i empaquetatge. Per aquestes raons, amb la present tesi doctoral es va desenvolupar un model matemàtic a través de dinàmica de sistemes que permetera analitzar l'impacte en les cadenes de subministrament que han apropiat el procés d'impressió 3d com un dels seus enfocaments de producció. Es va iniciar analitzant el desenvolupament de la manufactura additiva (MA) a través del temps per a determinar les variables que descriuen els canvis, l'estat de maduresa i el nivell de penetració en els sectors econòmics; per a aconseguir-ho, es van realitzar revisions de literatura i anàlisi bibliomètrica. Posteriorment, es va definir com a unitat d'anàlisi el sector salut a causa del grau d'apropiació de la MA en els processos d'atenció. Es va realitzar la caracterització de l'estat actual i la proposta d'escenaris que van ser analitzats a partir del model que simulés el comportament de cada escenari. Per als escenaris additius es va considerar el rol que exerceix el membre de la cadena que implementa el procés additiu i com això altera l'estructura, els processos de gestió i la relació entre els actors. Els resultats demostren l'alt potencial d'impacte de la MA, des de les baules de producció fins a l'acostament amb el client, respecte a la literatura està emergint la investigació respecte al desenvolupament de granges d'impressió i estructures atomitzades. Es van descriure els processos de gestió de la cadena i com el procés additiu permea en els rols, la dependència i autonomia que té cada membre; essent les variables amb major afectació els costos de producció i distribució, temps d'espera, resposta i intervencions, així com els resultats satisfactoris. S'explica a través del contrast de tres escenaris, un tradicional i dos additius la reducció de, almenys, el 50% del lead time de la cadena, 30% les quantitats d'unitats d'inputs i 20% la capacitat disponible. En contrast, encara s'evidencien grans reptes per a una adequada implementació, relacionats amb el coneixement, cobertura, poder d'adquisició econòmica i el nivell de resposta de la producció tradicional. Per a futures línies d'investigació s'assenyala la vinculació amb les altres tecnologies de la indústria 4.0, l'anàlisi de cadascun dels processos de gestió de la cadena i el desenvolupament de models que permeten la selecció de l'estructura més apropiada per a la inclusió de la MA a partir de simulació d'escenaris additius, entre altres. / [EN] The technological development, as a consequence of industrial revolutions, has generate that constantly in the manufacturing process, the production techniques has alter and replace, at the same time, it impacts the information flows, the financial flows and the materials flows in the supply chain. The additive manufacturing is considerate as a production technique with a high potential to impact the setting and the management of the demand through the custom results, adjust to the client needs, reducing times and costs of storage, transport and packing. For these reasons, with the present doctoral thesis a mathematic model has been developed through the dynamic of systems, that allowed to analyze the impact of the supply chains that has appropriate the 3d print process as one of its production approaches. The first step was to analyzed the additive manufacturing (AM) development through the time to determine the variables that describes the changes, the state of maturity and the permeation levels in the economic sector, to make it, it was made literature reviews and bibliometric analysis. Later, it was defined as an analysis unit the health care sector due to the appropriation of the AM in the attention process. A characterization of the actual state was made, and the scenario proposal were analyzed from the model that simulates the behavior on each scenario. For the additive scenario, it was considered the role that is performed the member of the chain that implements the additive process and how this alter the structure, the management process and the relation between the actors. The results, show a high potential on the impact of AM, from the production links to the approach with the client, about the literature, it is emerging the investigation of print farms development and atomized structures. The process of the chain management was described and how the additive process permeates the roles, the dependence and the autonomy that each member has; the variables with most affectation is, the production and distribution costs, the waiting times, response and interventions, also the satisfactory results. It is explaining through the contrast of three scenarios, one traditional and two additives, the reduction of, at least the 50% of the chain lead time, 30% the supplies quantity and 20% the available capacity. By contrast, it still evidences great challenges for a proper implementation, related with the knowledge, coverage, economic acquisition power and the response level of the traditional production. For future investigations, it is points out the bonding with the other technologies of the 4.0 industries, the analysis of each one of the management process of the chain and the model development, that allowed the selection of a proper structure for the inclusion of the AM from the simulation of additive scenarios, among others. / Núñez Rodríguez, J. (2021). Modelo para el análisis del impacto de la manufactura aditiva en la gestión de la cadena de suministro [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/180383

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