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In this context, the main objective of this project is to determine if 3D printed concreteformworks are able to not fall apart and later withstand the stresses produced byC40/50 and selfcompactingconcrete (SCC) castings. The purpose is to check thesuitability of this method applied to the construction of bridge pillars and its capabilityof covering and protecting the reinforcement placed in the casting. The methodconsists of the design and construction of the formworks, the casting of the SCCcolumns and the performance of compression and bond tests to samples extracted fromthe sections presented to check the resistance and the bond between the formwork andthe interior concrete casting.The results obtained showed that the formworks did not fall apart and could withstandthe stresses caused by the casting. In addition, the casting presented a better bond atthe bottom of the sections in both cases. Although C40/50 presented a higher bondand compression strength than SCC, it showed a bond problem at the top part thathighlighted the importance of vibrating the concrete mix properly.After analysing all the results a clear conclusion is not reached, so further research inthis field needs to be done in order to build bridge pillars with this technology.

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The Tissue Engineering Lab at California Polytechnic State University San Luis Obispo focuses on creating tissue-engineered Blood Vessel Mimics (BVMs) designed for the preclinical testing of neurovascular devices. These BVMs are composed of silicone models, representing anatomically accurate neurovasculatures, that are sodded with vascular cell types and then cultivated in bioreactors (which maintain physiologic conditions). These silicone models are currently sourced externally from industry partners, so the primary goal of this thesis was to develop the means and methods for the Tissue Engineering Lab to manufacture silicone models in-house. The first aim of this thesis was to develop and explore injection molding as a possible technique for manufacturing silicone models; this included prototyping various designs of molds, developing a viable workflow for injection molding, then assessing the resulting silicone models through measurement characterization, cytotoxicity screening, and BVM set-ups. The first aim found that injection molding was a viable manufacturing technique for making silicone models. The second aim of this thesis explored an alternative manufacturing method, dip-casting, to produce silicone models. The development of dip-casting was similar to injection molding, where several prototyping stages resulted in a viable workflow for making silicone models; the resulting silicone models were then assessed via measurement characterization and a BVM set-up. The second aim found that, in addition to injection molding, dip-casting was a viable technique for making silicone models, although the overall morphology of the resulting models was less desirable than those made by injection molding. The third and final aim of this thesis compared both manufacturing techniques (i.e., injection molding and dip-casting); this aim established that injection molding was preferable for making simple (less intricate) silicone models, whereas dip-casting was preferable for producing complex (more intricate) silicone models. Although the dip-casting technique requires more development to capture complex shapes and produce models with desirable morphologies, the injection molding protocol was formalized into a prescribed workflow for the Tissue Engineering Lab to reference. Overall, this thesis developed and explored two different manufacturing techniques for making silicone models and found that both were capable of making silicone models that could be used to create tissue-engineered BVMs, with injection molded models being ready to implement as the dip-casting process continues to be refined.

The female reproductive organs are among the few adult tissues in which periodic angiogenesis normally occurs. Pathological angiogenesis can occur in various conditions, such as solid tumors. Vascular endothelial growth factor (VEGF) signaling often represents a critical rate-limiting step in physiological and pathological angiogenesis. This study utilizes development of utero-ovarian vasculature during pregnancy in goats as a model of physiological angiogenesis. Non-pregnant does and does at 4, 7, 10, 13, 16, and 18 weeks of gestation were used. Arteries of the reproductive tract were injected <i>in situ</i> with Microfil®. The tracts were fixed, dehydrated, and rendered transparent to reveal the paths of arteries. The ovarian artery was tortuous and lay in close apposition to the uterine tributary of the ovarian vein in all specimens studied. In non-pregnant does, this arrangement may serve as a local utero-ovarian pathway for the corpus luteum (CL) luteolysis at the end of non-fertile estrous cycle. During pregnancy, this arterio-venous arrangement may transfer luteotropic substances from uterus to ovary, which may serve in maternal recognition of pregnancy and fit the fact that the goat is CL dependent throughout gestation. In some cases of triplets, the size of the uterine branch of the ovarian artery was equal to or even larger than that of its parent artery and/or the ipsilateral uterine artery; and the vaginal artery contributed a connecting branch to the uterine artery. These physiological adaptations of the ovarian and/or vaginal arteries correlate well with the increasing nutrient demands of the growing multiple fetuses. In a second experiment, the vasculature of the uterus and ovaries was injected <i>in situ</i> with a mixture of Batson's No.17® and methyl methacrylate and then processed for observation by SEM. The microvasculature differed between non-pregnant and pregnant does, and with advancing gestation. We concluded that goats possess a <i>multivillous</i> type placenta. Capillary sinusoids and crypts on the fetal surface of the caruncle may compensate for the negative effect of the increased interhemal distance. Intussusceptive angiogenesis should be considered as equally possible and important mechanism as sprouting angiogenesis during placental development. Capillary diameters increased significantly during pregnancy especially after 4 weeks. Capillary density index was 66.8, 68.7, 55.5, 63.5, 70.1, 70.4, 64.5 percent in non-pregnant, 4, 7, 10, 13, 16, and 18 weeks of pregnancy, respectively. In the ovary, coiling of the ovarian branch of the ovarian artery around the ovarian tributary of the ovarian vein was observed. This may represent a local channel required for product transport from ovarian vein to ovarian artery and might have a role in regulating blood pressure to various ovarian structures. Immunolocalization of VEGF was performed as a third experiment. Immunostaining was observed in cyto- trophoblasts, maternal epithelial tissues, and vascular endothelium and smooth muscle, but not in binucleate giant cells or connective tissue. No apparent differences were observed in intensity and pattern of VEGF staining associated with advancing gestation. Luteal and follicular cells, and endothelium and smooth muscles of the ovarian vasculature positively stained. Patterns and intensity of staining of VEGF suggest that the fetus is directing its own survival by producing growth factors affecting fetal and maternal tissues. VEGF may have a role in growth and differentiation of cytotrophoblasts, as well as, development and maintenance of CL. In the fourth experiment, the sequential expression of VEGF and its receptors (fms-like tyrosine kinase, Flt-1 and kinase-insert domain-containing receptor, KDR) was measured using real-time quantitative PCR. Targets were detected in all studied tissues; however, levels of expression differed according to the stage of pregnancy. Expression of VEGF and its receptor mRNAs increased with advancing pregnancy, which correlates with the expansion of vasculature during pregnancy. Differences in the time-courses of the expression of Flt-1 and KDR mRNAs during pregnancy suggest that each receptor plays a different role in the angiogenic process. As an application of our model of angiogenesis, we tested the effect of swainsonine (active compound of locoweed and a potential anti-cancer drug) on the process. Does treated with swainsonine were euthanized at 7 and 18 weeks. No significant differences were found in sinusoidal diameters in treated does at 7 weeks, but a decrease in capillary density index was noted. In the ovary, focal avascular areas were observed in the corpus luteum of swainsonine-treated does at 7 weeks of pregnancy. Swainsonine caused great distortion in the uterine and ovarian vasculature at 18 weeks. A decrease in intensity of the immunoreactivity to VEGF antibody was observed in tissues from swainsonine-treated does at 7 and 18 weeks. There was no substantial effect of swainsonine on the expression of VEGF and its receptors' mRNAs in any of the studied tissues (except in the left ovary, where it had an inhibitory effect) at 7 weeks of pregnancy, but it had an inhibitory effect at 18 weeks. Demonstration of swainsonine's potential to negatively affect vascular development and suppress genes likely involved in angiogenesis at critical stages of blood vessel proliferation lends credibility to its potential as anti-cancer drug. / Ph. D.

Tesis por compendio / Biodegradable active films based on poly(lactic) acid (PLA) and starch were developed and characterized as to their functional and structural properties, using the bilayer film strategy, in order to obtain materials that better meet the food packaging requirements. Plasticization of semicrystalline PLA was analysed by using three different biodegradable compounds to enhance the PLA mechanical performance. Likewise, cinnamaldehyde was incorporated to PLA-starch bilayer films and their antimicrobial properties and release kinetics in food simulants were analysed. Semicrystalline and amorphous PLA and cassava starch (S) were used to obtain the films. Semicrystalline PLA and S were processed by melt blending and compression moulding, whereas amorphous PLA films were obtained by casting the ethyl acetate solution of the polymer, with and without cinnamaldehyde. Bilayer films were obtained by compression moulding of amorphous PLA layers with starch sheets, while semicrystalline PLA sheets were also used in bilayers for comparison purposes. The analyses of crystallization behaviour and glass transition of neat and plasticized semicrystalline PLA films revealed an increase in the crystallinity, along with a reduction in the glass transition temperature (Tg), in line with the rise in plasticizer concentration in every case. Despite the decrease in Tg, the tensile test did not reflect an enhancement of the film elongation capacity, in comparison to the non-plasticized polymer. Likewise, plasticizers did not reduce the film elastic modulus due to the greater induced crystallinity. On the basis of these results, a more extensible material, amorphous PLA, was considered to obtain PLA-starch bilayer films, taking advantage of the complementary barrier properties of both polymers and the high mechanical resistance of PLA. Despite the lower ratio of PLA sheet in the starch bilayer assembly (about 1/3 of the film thickness), a great improvement in tensile and water vapour barrier properties was achieved with respect to the neat starch films, the films maintaining high transparency and oxygen permeability as low as that of starch films. When cinnamaldehyde was included in the cast PLA sheet, films became thinner due to the losses of the volatile active during processing, but the improvement in barrier properties was maintained, with lower mechanical resistance. Thermal analyses revealed diffusion of cinnamaldehyde or low molecular weight compounds from the amorphous PLA layer to the adhered sheets (starch or semicrystalline PLA) which contributed to their plasticization and reduced the PLA crystallization. Antimicrobial activity of the cinnamaldehyde-loaded films against Gram- (Escherichia coli) and Gram+ (Listeria innocua) bacteria was tested through in vitro tests. Both amorphous PLA monolayers and starch-PLA bilayers were effective at controlling the bacterial growth, thus indicating that the active amount released into the growth medium exceeded the minimum inhibitory concentration (MIC) of both bacteria, despite the losses of the active compound during the film processing. In contrast, PLA-cinnamaldehyde loaded PLA bilayer films did not show antimicrobial activity. The analysis of the release kinetics of cinnamaldehyde from the films to the different food simulants revealed differing behaviours of the active compound delivery, depending on both films and food simulants. PLA bilayer films exhibited the slowest cinnamaldehyde release and the predicted amount delivered into the aqueous culture medium did not reach the MIC, explaining the lack of antimicrobial effect of these films. Therefore, the developed bilayer films based on amorphous PLA and starch represent an interesting strategy to obtain high barrier-highly resistant packaging films, with active properties when they include cinnamaldehyde as antimicrobial compound. / Se han desarrollado films biodegradables activos a base de ácido poliláctico (PLA) y almidón y se han caracterizado en sus propiedades funcionales y estructurales. Se ha utilizado la estrategia de films bicapa para obtener materiales con propiedades más ajustadas a los requerimientos del envasado de alimentos. Se ha estudiado la plastificación del PLA semicristalino con tres compuestos biodegradables para mejorar la extensibilidad del PLA. Así mismo, se ha incorporado cinamaldehído a los films bicapa PLA-almidón y se ha analizado su capacidad antimicrobiana y su cinética de liberación en simulantes alimentarios. Se han utilizado PLA semicristalino y amorfo y almidón de yuca para la obtención de los films. El PLA semicristalino y el almidón se han procesado por mezclado en fundido y termocompresión, mientras que los films de PLA amorfo se han obtenido por extensión y secado de su disolución en acetato de etilo, con y sin cinamaldehído. Los films bicapa se han obtenido por termocompresión de las láminas de PLA amorfo con las de almidón, y también con las de PLA semicristalino para su comparación. El análisis de la cristalización y transición vítrea del PLA semicristalino, con y sin plastificantes, reveló un incremento en la cristalinidad, junto a la reducción de la temperatura de transición vítrea (Tg), al aumentar el contenido en plastificante, en todos los casos. No obstante, a pesar del descenso en la Tg, no se obtuvo un incremento en la extensibilidad de los films. Así mismo, los plastificantes no redujeron el módulo de elasticidad debido al aumento de la cristalinidad. En base a estos resultados, se optó por un material más extensible, el PLA amorfo, para la obtención de los films bicapa con almidón, aprovechando la complementariedad de propiedades de barrera de ambos polímeros y la alta resistencia mecánica del PLA. A pesar de la baja proporción de la capa de PLA en la bicapa (aproximadamente 1/3 del grosor del film), se obtuvo una gran mejora en las propiedades mecánicas y de barrera con respecto a los films de solo almidón; manteniendo una alta transparencia y una permeabilidad al oxígeno tan baja como la de los films de almidón. Cuando se incluyó cinamaldehído en la capa de PLA amorfo, los films fueron más finos debido a las pérdidas del volátil durante el procesado, pero se mantuvo la mejora en propiedades de barrera, con films un poco menos resistentes. El análisis térmico reveló la difusión del cinamaldehído u otros compuestos de bajo peso molecular desde la capa de PLA amorfo a las capas adheridas (almidón o PLA semicristalino), lo que contribuyó a su plastificación y redujo la cristalización del PLA. La actividad antimicrobiana de los films con cinamaldehído contra bacterias Gram- (Escherichia coli) y Gram+ (Listeria innocua) se analizó mediante test in vitro. Tanto las monocapas de PLA amorfo como las bicapas de almidón-PLA fueron efectivas en el control del crecimiento microbiano de ambas bacterias, lo que indicó que, a pesar de las pérdidas de cinamaldehído, la cantidad liberada al medio de cultivo superó la concentración mínima inhibitoria (MIC) de ambas bacterias. Por contra, la bicapa de PLA con cinamaldehído no mostró actividad antimicrobiana. El análisis de la cinética de liberación del cinamaldehído de los films en los diferentes simulantes reveló diferencias de comportamiento en la liberación del activo dependiendo del tipo de film y simulante. Las bicapas de PLA presentaron la liberación más lenta y la cantidad liberada predicha en medios acuosos, como él del cultivo, no alcanzó la MIC de las bacterias, lo que explicó la falta de actividad antimicrobiana observada para estos films. Por lo tanto, los films bicapa desarrollados con PLA amorfo y almidón representan una estrategia interesante para obtener films de envasado de alta barrera y buena resistencia mecánica, con propiedades activas cuando incluyen cinamaldehído como / S'han obtingut films films biodegradables actius de àcid polilàctic (PLA) i midó i s'han caracteritzat en les seues propietats funcionals i estructurals. S'ha utilitzat l'estratègia de films bicapa per obtindré materials amb propietats mes properes als requeriments de l'envasat d'aliments. S'ha estudiat la plastificació del PLA semicristal·lí amb tres compostos biodegradables per a millorar l'extensibilitat del PLA. Així mateix, s¿ha incorporat cinamaldehido als films bicapa de PLA-midó i s'ha analitzat la seua capacitat antimicrobiana i la seua cinètica d'alliberació en simulants alimentaris. S'han utilitzat pla semicristal·lí i amorf i midó de iuca per a l'obtenció del films. El PLA semicristal·lí i el midó s¿han processat mitjançant mescla en fos i termocompressió, mentre que els films de PLA amorf s¿han obtingut mitjançant extensió i assecat de la seua dissolució en acetat de etilo, amb i sense cinamaldehido. Els films bicapa s'han obtingut per termocompressió de les lamines de PLA amorf junt les de midó, i també amb les de PLA semicristal·lí per a la seua comparació. L'anàlisi de la cristal·lització i transició vitrea del PLA semicristal·lí, amb i sense plastificants, va revelar un increment en la cristall·initat, a mes de una reducció de la temperatura de transició vitrea (Tg), a l'augmentar el contingut en plastificant, en tots els casos. No obstant això, a pesar del descens en la Tg, no s'obtingué un increment en l'extensibilitat dels films. Així mateix, els plastificants no van reduir el mòdul d'elasticitat a causa de l'augment de la cristal·linitat. Basant-se en estos resultats, es va optar per un material més extensible, el PLA amorf, per a l'obtenció dels films bicapa amb midó, aprofitant la complementarietat de propietats de barrera d'ambdós polímers i l'alta resistència mecànica del PLA. A pesar de la baixa proporció de la capa de PLA en la bicapa (aproximadament 1/3 del grossor del film), s'obtingué una gran millora en les propietats mecàniques i de barrera respecte als films de només midó; mantenint una alta transparència i una permeabilitat a l'oxigen tan baixa com els films midó. Quan es va incloure cinamaldehido en la capa de PLA amorf, els films van ser més fins a causa de les pèrdues del volàtil durant el processat, però es mantingué la millora en propietats de barrera, amb films un poc menys resistents. L'anàlisi tèrmic va revelar la difusió del cinamaldehido o altres compostos de baix pes molecular des de la capa de PLA amorf a les capes adherides (midó o PLA semicristal·lí), la qual cosa va contribuir a la seua plastificació i va reduir la cristal·lització del PLA. L'activitat antimicrobiana dels films amb cinamaldehido contra bacteris Gram- (Escherichia coli) i Gram+ (Listeria innocua) es va analitzar per mitjà de test in vitro. Tant les monocapes de PLA amorf com les bicapes de midó-PLA van ser efectives en el control del creixement microbià d'ambdós bacteris, la qual cosa va indicar que, a pesar de les pèrdues de cinamaldehido, la quantitat alliberada al mig de cultiu va superar la concentració mínima inhibitòria (MIC) d'ambdós bacteris. Per contra, la bicapa de PLA amb cinamaldehido no va mostrar activitat antimicrobiana. L'anàlisi de la cinètica d'alliberament del cinamaldehido dels films en els diferents simulants va revelar diferències de comportament en l'alliberament de l'actiu depenent del tipus de film i simulant. Les bicapes de PLA van presentar l'alliberament més lent i la quantitat alliberada predita en mitjans aquosos, com el del cultiu, no va aconseguir la MIC dels bacteris, la qual cosa va explicar la falta d'activitat antimicrobiana observada per a estos films. Per tant, els films bicapa obtinguts amb PLA amorf i midó representen una estratègia interessant per a obtindre films d'envasament d'alta barrera i bona resistència mecànica, amb propietats actives quan inclouen cinamaldehido com antimic / Muller, J. (2017). Films activos para el envasado de alimentos a base de ácido Poliláctico (PLA) y almidón [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/89084 / Compendio

This thesis presents a comprehensive investigation into the feasibility and optimization of self-piercing riveting (SPR) for joining high-ductility die-cast aluminum alloy Nemalloy HE700 in F temper (as-cast) condition to dissimilar sheet materials, namely wrought aluminum alloy 6082-T6 and dual-phase steel DP600. The study demonstrates successful SPR joining of HE700 to these materials, with optimized process parameters and joint quality meeting automotive industry standards. Systematic experimental studies were conducted to investigate the effects of key SPR process parameters, including die geometry, ring groove depth, rivet hardness, and length, on joint quality and performance. Microstructural characterization revealed distinct patterns of grain flow and localized hardening in HE700 around the rivet and die features, providing insights into its deformation characteristics. Finite element simulations, incorporating advanced material models such as Johnson-Cook plasticity and failure for AA6082 and DP600, and Voce hardening with Gurson-Tvergaard-Needleman void damage model for HE700, were developed and extensively validated against experimental results. The simulations accurately predicted potential failure sites in HE700, aligning with experimental observations of crack initiation. Numerical parametric studies demonstrated the intricate effects of process parameters and material properties on the stress and strain distributions, material flow, and damage accumulation during SPR. The research contributes to the growing body of knowledge on advanced joining techniques for dissimilar materials, supporting vehicle lightweighting efforts. It establishes a comprehensive methodology integrating experiments, microstructural characterization, and simulations for studying and optimizing SPR processes for low ductility casting alloys, serving as a blueprint for future research and industrial implementation. The findings demonstrate the viability and potential of SPR technology for integrating high-ductility die-cast aluminum alloy HE700 into lightweight automotive body structures, paving the way for its wider industrial adoption. / Thesis / Master of Applied Science (MASc) / This research explores the potential of using a novel high-ductility aluminum alloy, Nemalloy HE700, in self-piercing riveting (SPR) - a modern joining technique for automotive manufacturing. The study aims to optimize the SPR process for joining HE700 to other commonly used automotive materials, such as aluminum alloys and high-strength steels, without compromising joint quality. By conducting practical experiments and computer simulations, the research identifies the best process parameters, such as rivet design and die shape, that result in strong, reliable joints meeting automotive industry standards. The findings demonstrate the successful use of HE700 in SPR, offering a promising solution for creating lighter, more fuel-efficient vehicles. This work contributes to the development of advanced joining technologies for sustainable transportation, making vehicles more environmentally friendly while maintaining high performance and safety standards.

Freeze casting is a colloidal processing technique that shows great promise for development of nanostructured materials. A ceramic nanopowder is dispersed with a polymer in water, under carefully controlled pH. The suspension is cast into a suitable mold and frozen, then de-molded and exposed to a vacuum to sublimate and remove the water. Polymer adsorption and rheology were studied to optimize and characterize a colloidal suspension of a 38 nm Al2O3 powder. The dispersant, dispersant amount, pH and solids loading were examined to determine the best conditions for freeze casting. Based on adsorption and viscosity data, optimal conditions for freeze casting were found with Poly(acrylic acid) (PAA) dispersant, at 2.00 wt% (of Al2O3), pH of 9.5, and a solids loading of 40 vol%. Carbon nanotubes (CNTs) were added to that suspension in increments of 0.14, 0.28, 0.53, 1.30 and 2.60 vol%. The viscosity increased dramatically upon addition of 1.30 vol% CNTs. The colloidal CNT-Al2O3 suspension was successfully freeze cast and the microstructure showed a very smooth fracture surface. It was determined that upon resting, the suspension undergoes a physical change which must be completed to obtain advantageous microstructure. Freeze cast Al2O3 discs with and without CNTs were measured using a concentric ring test, with strengths on the order of one MPa. The freeze cast sample was successfully debinded, but the heating profile attempted was not effective in obtaining full density. / Master of Science