This masters thesis investigates the influence of various printing parameters on the shape memory effect of 3D printed objects, with a focus on fixity and recovery rates. Through a series of experimental tests, it was observed that printing temperature had minimal impact on fixity and recovery rates. However, correlations were identified between fixity rate and layer height, as well as between percentage infill and recovery rates. Lengthwise shrinkage, particularly prominent in samples with 0\% infill, was attributed to printing speed the formation of voids within the structure and layer height. Higher printing speeds were found to compromise mechanical properties while facilitating enhanced shape transformation responses. Additionally, changes in layer height led to observable alterations in the printed object's geometry, including bending and bulging, due to retained shape memory of the filaments original form. Moreover, certain 100\% infill samples exhibited an unexpected hardening phenomenon akin to annealing. These findings underscore the intricate interplay of printing parameters in determining shape memory properties, mechanical properties and highlight potential avenues for optimization in 3D printing processes.

The presence of living organisms in a fluid can affect a fluid’s properties. Organisms propel themselves through the fluid using specialised organelles that generate propulsion. This propulsion creates disturbances in the fluid, leading to variations in its properties. The overarching research question is: ”Can the properties of a fluid be modified with biologically active suspensions?”. Organisms respond to their environment for survival and thereby induce intriguing patterns which enhance flows. By using their natural instincts to react to external stimuli, fluid systems could generate flows or intrinsically modify their properties, which can be controlled by a user’s own will. It is thought that the local orientation of the organism influences the viscosity in a shear flow, because of the added stress induced by the activity of the organisms. This research investigates the influence of the orientation of the stress induced by the green alga Chlamydomonas reinhardtii on the viscosity using light-controlled rheology. This is done through two research questions: ”Is it possible to modulate the swimming orientation of the green algae using a light source?”, followed by the question: ”Can we thereby control the viscosity of the algal sample?”. Phototaxis is the natural response of the algae to swim in the direction of light and was the main asset used to control the swimming orientation. The first research question was explored through three-dimensional microscopy. Images were acquired from algae controlled by light entering at a specific angle of 45°. The second research question com bined light-control with a rheometer that imposed an external shear flow. The rheometer measures the viscosity of light-controlled algae using an on-and-off light cycle. Through the three-dimensional imaging, the position and velocity vectors of each par ticle was found and converted into the relevant spherical coordinates which in turn could present the trajectories of the organisms. These were found to be swimming at the tar geted angle at sufficient light intensity. The second experiment however showed ambiguous viscosity responses that had to be quantified using power analysis. The quantification of the data showed possibility of a viscosity change as a result of the reorientation towards light. The first experiment showed the possibility to control the orientation of the algae using phototaxis and thus positively answering the first research question. The second research question cannot be answered taking strong conclusions. The quantification of the data showed possibility of a viscosity change as a result of the reorientation towards light.

Algae remains a focal point of scientific inquiry with its wide-ranging environmental, health, and energy applications. Among model organisms, the unicellular green alga Chlamydomonas reinhardtii holds significance, particularly in light of its responsiveness to temperature alterations impacting swimming velocity. Notably, this study investigates the intriguing ability of live Chlamydomonas cells to modulate suspension viscosity compared to non-living particles.

Under shear flow conditions, a captivating phenomenon termed "heat thickening" is unveiled in live algae suspensions. Unlike conventional fluids, heightened temperatures uniquely enhance viscosity in these suspensions due to the interplay between cell-generated stresslets and shear flow. This study aims to characterize the influence of temperature on microalgal swimming speeds, flagella beating frequencies, and its role in viscosity modulation.

An experimental setup with precise temperature control and water circulation is employed to achieve this. Both 2D and 3D tracking methods measure motility and inform the findings. Results demonstrate that swimming velocity and beating frequency increase with temperature until 35 degrees Celsius, followed by a decline. This trend aligns with the observed live cell suspension viscosity measurements, indicating the impact of motility on suspension rheology.

Quantitative research has indicated the simultaneous influence of beating frequency and swimming velocity on suspension viscosity, underscoring the importance of investigating motility's role. This study suggests that the motility of live algae cells holds the potential for interpreting and modulating suspension rheology, warranting further exploration under various temperature conditions. Such insights contribute to understanding algae behavior and its applications across environmental and industrial contexts.

This thesis investigates the ability of Bayesian EUCLID to retrieve a predictive approximate material model for the myocardium in the presence of heterogeneous deformation fields due to simulated biaxial stretch tests. The Holzapfel-Ogden material model is used as the ground-truth material model of the simulation, since it is capable of describing the orthotropic and hyperelastic behavior of the myocardium. In total, four material models were retrieved from Bayesian-EUCLID by considering two fiber orientations within the sample and two displacement measurement techniques. The two fiber directions included one in which the sheet-like structure of the sample lies within the test plane and one in which it lies perpendicular to the test plane. The displacement field measurements considered were a full displacement field measurement and an approximation thereof based on a stereo digital image correlation method. The results show that when the sheet-like structure of the myocardium lies within the test plane of the biaxial stretch test and the full displacement field is available, Bayesian EUCLID is capable of finding orthotropic and hyperelastic material models that correspond well to the ground truth. This shows that a biaxial stretch test can adequately characterize the material behavior of the myocardium.