Search

published

Das Verstehen und Interpretieren von volumetrischen multidimensionalen Daten ist eine komplexe und kognitiv anstrengende Aufgabe. Vor allem im Bereich der Materialwissenschaften ist die Exploration umfangreicher räumlicher Daten zwingend notwendig. Die zerstörungsfreie Prüfung (NDT) spielt in der industriellen Produktion vor allem im Bereich der Material- und Bauteilprüfung eine wesentliche Rolle hinsichtlich der Analyse, Visualisierung und Optimierung von neuen, hochkomplexen Materialsystemen wie Faserverbundwerkstoffen. Um die steigenden Anforderungen an diese Materialien und Komponenten der Zukunft in industriellen Anwendungen zu gewährleisten, sind umfangreiche Inspektionen und Kontrollen essentiell. Die durch bildgebende Verfahren wie Röntgencomputertomographie (XCT) generierten NDT-Prüfdaten umfassen neben 2D Bildern volumetrische Modelle, und daraus abgeleitete hochdimensionale Datenräume und können oft nicht, oder nur bedingt, auf Desktopmonitoren mittels Standard-2D-Visualisierungstechniken evaluiert werden. Daher wurden in dieser Arbeit neue immersive Visualisierungs- und Interaktionstechniken mittels Virtual Reality (VR) zur Untersuchung dieser hochkomplexen, heterogenen Materialsysteme entwickelt. Wir präsentieren eine neue Technik namens "Modell in Miniatur"{} zur effektiven interaktiven Exploration und visuellen Analyse der Faser-Charakteristiken. Weiters kombinieren wir verschiedene Ansätze wie Explosionsdarstellungen, Histogramme und Knoten-Kanten Diagramme, um einzigartige Einsichten in die Verbundwerkstoffe zu ermöglichen. Unter Einsatz körperlicher Interaktion und Navigation, und der Erweiterung der Fähigkeiten des Nutzers, sind bisher unmögliche Einblicke in komplexe Materialstrukturen möglich. Dabei setzen wir neue Erkenntnisse der immersiven Analyse ein, um die räumlichen Daten begreifbar zu machen und testen die Ergebnisse in einer qualitativen Studie mit Fachexperten. Die Evaluation unserer Techniken zeigt positive Resultate, die für einen Nutzen der immersiven Analyse von Verbundwerkstoffen und für die Exploration von allgemeinen hochdimensionalen Volumen spricht. Die gewonnenen Einsichten stellen damit einen wichtigen Schritt zur Weiterentwicklung zukünftiger immersiver Analyseplattformen dar., Understanding and interpreting volumetric multidimensional data is a complex and cognitively demanding task. Especially in the field of material science the exploration of large spatial data is crucial. Non-destructive testing (NDT) plays an essential role in industrial production, especially in the field of material and component testing, regarding the analysis, visualization, and optimization of new, highly complex material systems such as fiber composites. In order to support the increasing demands on these materials and components of the future in industrial applications, extensive inspections and controls are essential. NDT inspection data generated by imaging techniques such as X-ray computed tomography (XCT) include 2D images, volumetric models, and derived high-dimensional data spaces. They can rarely, or only to a limited extent, be evaluated on desktop monitors using standard 2D visualization techniques. Therefore, novel immersive visualization and interaction techniques using Virtual Reality (VR) were developed in this thesis to investigate highly complex, heterogeneous material systems. We present a novel technique called "Model in Miniature" for an effective and interactive exploration and visual analysis of fiber characteristics. Furthermore, we combine different approaches like exploded views, histograms, and node-link diagrams to provide unique insights into the composite materials. Using embodied interaction and navigation, and enhancing the user's abilities, previously impossible insights into the most complex material structures are possible. We use the latest findings from the field of Immersive Analytics to make the spatial data more comprehensible and test the results in a qualitative study with domain experts. The evaluation of our techniques has shown positive results, which indicate the benefits of an immersive analysis of composite materials and the exploration of overall high-dimensional volumes. The insights gained therefore represent an important step towards the further development of future immersive analysis platforms.

Probing of biomolecular complexes by single-molecule force spectroscopy (SMFS) methods including AFM requires proper and suitable coupling methods for immobilization of biomolecules onto the AFM tip and the surface. The use of flexible tethers for the coupling process has dual advantages. First, they allow the specific immobilization of interacting molecules, and second, their flexibility facilitates the proper orientation of the interacting partners. Recently, we developed an approach termed Flexible Nano Array (FNA) in which interacting partners are located on the same polymeric FNA molecule separated by a flexible segment with a defined length. In this paper, we modified the FNA tether approach by incorporating click chemistry with non-metal modification. FNA was synthesized using DNA synthesis chemistry, in which phosphoramidite (PA) spacers containing six ethylene glycol units were used instead of nucleoside triphosphates. During the synthesis, two T modifiers conjugated to two dibenzocyclooctyl (DBCO) residues were incorporated at selected positions within the FNA. The DBCO functionality allows for coupling azide labeled biomolecules via click chemistry. Amyloid peptide Aβ(14-23) terminated with azide was incorporated into the FNA and the reaction was controlled with mass-spectrometry. Assembly of tethered Aβ(14-23) peptides into dimers was characterized by AFM force spectroscopy experiments in which the AFM tip functionalized with FNA terminated with biotin probed a streptavidin-coated mica surface. The formation of the peptide dimer was verified with force spectroscopy that showed the appearance of a specific fingerprint for dimer dissociation followed by a rupture event for the biotin-streptavidin link. The developed approach is capable of multiple probing events to allow the collection of a large set of data for a quantitative analysis of the force spectroscopy events.

Progress towards rapid and simple characterization of biomolecular samples by scanning probe microscopy is impeded mainly by limitations of the current approach to sample preparation. We are working on approaches based on chemical functionalization of mica. Treatment of mica with aminopropyltriethoxy silane (APTES) makes the surface positively charged (AP-mica) and able to hold DNA in place for imaging, even in water. We have shown that AP-mica is an appropriate substrate for numerous nucleoprotein complexes as well. The AFM images of the complex of DNA with RecA protein are stable and indicate a structural periodicity for this filament. AP-mica holds strongly such large DNA complexes as kinetoplast DNA (kDNA) and is an appropriate substrate for their imaging with AFM. We have further develop this approach for making hydrophobic substrates. Silylation of mica surface with hexamethyldisilazane (Me-mica) allowed us to get AFM images of chlorosomes, an antenna complex isolated from green photosynthetic bacteria. Me-mica may be converted into a positively charged substrate after treatment with water solutions of tetraethylammonium bromide or cetyltrimethylammonium bromide. These activated surfaces show high activity towards binding the DNA molecules.