Development of cold-forming technologies for the construction of concrete reef structures

[EN] En aquesta Tesi de Màster, l'objectiu és avançar en el disseny i tecnologies per produir elements de formigó a base de làmines primes fabricades seguint el concepte de deformació en fred de formigons reforçats amb fibres d'ultra altes prestacions (UHPFRC). Per això es porta a terme una investigació realitzada en tres fases. En la primera fase s'aplica un assaig de temps d'enduriment per definir la influència d'additius acceleradors en l'enduriment d'aquests formigons. En la segona fase es fabriquen provetes compactades a diferents temps (edats) en relació als temps d'enduriment avaluats en la primera fase. La influència d'aquests temps d'espera en la resistència del formigó ha estat analitzada. En l'última fase s'avalua la possibilitat de crear fines làmines conformades a base d'una vibració de superfície. S'estudien diferents temps d'espera abans d'aplicar la vibració amb l'objectiu que la peça formada conservi la forma en el motlle convex, i s'aconsegueixi un bon acabat superficial.[CA] En aquesta Tesi de Màster, l'objectiu és avançar en el disseny i tecnologies per produir elements de formigó a base de làmines primes fabricades seguint el concepte de deformació en fred de formigons reforçats amb fibres d'ultra altes prestacions (UHPFRC). Per això es porta a terme una investigació realitzada en tres fases. En la primera fase s'aplica un assaig de temps d'enduriment per definir la influència d'additius acceleradors en l'enduriment d'aquests formigons. En la segona fase es fabriquen provetes compactades a diferents temps (edats) en relació als temps d'enduriment avaluats en la primera fase. La influència d'aquests temps d'espera en la resistència del formigó ha estat analitzada. En l'última fase s'avalua la possibilitat de crear fines làmines conformades a base d'una vibració de superfície. S'estudien diferents temps d'espera abans d'aplicar la vibració amb l'objectiu que la peça formada conservi la forma en el motlle convex, i s'aconsegueixi un bon acabat superficial.[ES] En esta Tesis de Máster, el objetivo es avanzar en el diseño y tecnologías para producir elementos de hormigón a base de láminas delgadas fabricadas siguiendo el concepto de deformación en frio de hormigones reforzados con fibras de ultra altas prestaciones (UHPFRC). Para ello se lleva a cabo una investigación realizada en tres fases. En la primera fase se aplica un ensayo de tiempos de fraguado para definir la influencia de aditivos aceleradores en el endurecimiento de estos hormigones. En la segunda fase se fabrican probetas compactadas a diferentes tiempos (edades) en relación a los tiempos de fraguado evaluados en la primera fase. La influencia de estos tiempos de espera en la resistencia del hormigón ha sido analizada. En la última fase se evalúa la posibilidad de crear finas láminas conformadas a base de una vibración de superficie. Se estudian distintos tiempos de espera antes de aplicar la vibración con el objetivo de que la pieza formada conserve la forma en el molde convexo, y se consiga un buen acabado superficialVan Nuffel, E. (2018). Development of cold-forming technologies for the construction of concrete reef structures. http://hdl.handle.net/10251/114922Archivo delegad

Supporting the development and adoption of automatic lameness detection systems in dairy cattle : effect of system cost and performance on potential market shares

Most automatic lameness detection system prototypes have not yet been commercialized, and are hence not yet adopted in practice. Therefore, the objective of this study was to simulate the effect of detection performance (percentage missed lame cows and percentage false alarms) and system cost on the potential market share of three automatic lameness detection systems relative to visual detection: a system attached to the cow, a walkover system, and a camera system. Simulations were done using a utility model derived from survey responses obtained from dairy farmers in Flanders, Belgium. Overall, systems attached to the cow had the largest market potential, but were still not competitive with visual detection. Increasing the detection performance or lowering the system cost led to higher market shares for automatic systems at the expense of visual detection. The willingness to pay for extra performance was (sic)2.57 per % less missed lame cows, (sic)1.65 per % less false alerts, and (sic)12.7 for lame leg indication, respectively. The presented results could be exploited by system designers to determine the effect of adjustments to the technology on a system's potential adoption rate

Three-dimensional time-of-flight secondary ion mass spectrometry imaging of primary neuronal cell cultures

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has proven its ability to characterise (in)organic surfaces, and is increasingly used for the characterisation of biological samples such as single cells. By combining ion imaging and molecular depth profiling it is possible to render 3D chemical images, which provides a novel, label-free way to investigate biological systems. Major challenges lie, however, in the development of data analysis tools and protocols that preserve the cell morphology. Here, we develop and employ such tools and protocols for the investigation of neuronal networks. One of the reasons 3D ToF-SIMS imaging of cells is underused is the lack of powerful data analysis tools as 3D ToF-SIMS measurements generate very large data sets. To address this issue, we developed a method that allows the application of principal component analysis (PCA) to be expanded to large 3D images making 3D ToF-SIMS image processing of whole, intact cells and cellular networks with multivariate analysis now accessible on a routine basis. Using this method, we are able to separate cellular material from the substrate and can then correct z-offsets due to the cells' topography resulting in a more accurate surface heightmap. The method also facilitates differentiation between cellular components such as lipids and amino acids allowing the cell membrane, the cytoplasm and the extracellular matrix (ECM) to be easily distinguished from one another. These developments permit us to investigate the intracellular localisation of specific native and non-native compounds label-free, not just in single cells but also in larger cellular networks. The visualisation of the cellular uptake of non-native compounds, namely fluorescent dyes, in primary rat cortical neurons and the chemical differentiation between cell types, namely primary rat cortical neurons and retinal pigment epithelium (RPE) cells, are presented as applications. Even though the dyes have distinct fragment ions in the high mass range, it was not possible to detect the fluorophores by 3D ToF-SIMS imaging of freeze-dried cells. However, it was possible to detect distinct differences in the kind of ions detected for freeze-dried primary rat cortical neurons and RPE cells albeit in the low mass range. To obtain meaningful results, however, it is paramount that sample preparation does not induce significant physical or chemical changes. We present the first comprehensive comparison between large 3D ToF-SIMS images of freeze-dried and frozen-hydrated cells using PCA to facilitate the data analysis of these large data sets. A higher degree of colocalisation of the K+ signal with cell regions is observed for frozen-hydrated cells, which indicates a lower degree of membrane damage and migration of diffusible chemical species. Frozen-hydrated cell samples are therefore considered to best reflect the native cell state, but freeze-dried cell samples allow far easier sample handling. The mass spectrum of frozen-hydrated cellular material also has increased ion intensities for higher-mass fragments, which is an additional advantage, because the poor signal-to-noise ratio of molecular species with m/z > 200 is a major bottleneck in the advancement of ToF-SIMS imaging as a diagnostic tool

Een Germaanse gemeenschap op het spoor : een petrografische studie van Germaans aardewerk uit Bachte-Maria-Leerne (prov. Oost-Vlaanderen)

A

Three-dimensional time-of-flight secondary ion mass spectrometry imaging of primary neuronal cell cultures

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has proven its ability to characterise (in)organic surfaces, and is increasingly used for the characterisation of biological samples such as single cells. By combining ion imaging and molecular depth profiling it is possible to render 3D chemical images, which provides a novel, label-free way to investigate biological systems. Major challenges lie, however, in the development of data analysis tools and protocols that preserve the cell morphology. Here, we develop and employ such tools and protocols for the investigation of neuronal networks. One of the reasons 3D ToF-SIMS imaging of cells is underused is the lack of powerful data analysis tools as 3D ToF-SIMS measurements generate very large data sets. To address this issue, we developed a method that allows the application of principal component analysis (PCA) to be expanded to large 3D images making 3D ToF-SIMS image processing of whole, intact cells and cellular networks with multivariate analysis now accessible on a routine basis. Using this method, we are able to separate cellular material from the substrate and can then correct z-offsets due to the cells' topography resulting in a more accurate surface heightmap. The method also facilitates differentiation between cellular components such as lipids and amino acids allowing the cell membrane, the cytoplasm and the extracellular matrix (ECM) to be easily distinguished from one another. These developments permit us to investigate the intracellular localisation of specific native and non-native compounds label-free, not just in single cells but also in larger cellular networks. The visualisation of the cellular uptake of non-native compounds, namely fluorescent dyes, in primary rat cortical neurons and the chemical differentiation between cell types, namely primary rat cortical neurons and retinal pigment epithelium (RPE) cells, are presented as applications. Even though the dyes have distinct fragment ions in the high mass range, it was not possible to detect the fluorophores by 3D ToF-SIMS imaging of freeze-dried cells. However, it was possible to detect distinct differences in the kind of ions detected for freeze-dried primary rat cortical neurons and RPE cells albeit in the low mass range. To obtain meaningful results, however, it is paramount that sample preparation does not induce significant physical or chemical changes. We present the first comprehensive comparison between large 3D ToF-SIMS images of freeze-dried and frozen-hydrated cells using PCA to facilitate the data analysis of these large data sets. A higher degree of colocalisation of the K+ signal with cell regions is observed for frozen-hydrated cells, which indicates a lower degree of membrane damage and migration of diffusible chemical species. Frozen-hydrated cell samples are therefore considered to best reflect the native cell state, but freeze-dried cell samples allow far easier sample handling. The mass spectrum of frozen-hydrated cellular material also has increased ion intensities for higher-mass fragments, which is an additional advantage, because the poor signal-to-noise ratio of molecular species with m/z > 200 is a major bottleneck in the advancement of ToF-SIMS imaging as a diagnostic tool