Interactive visualization of intercluster galaxy structures in the horologium-reticulum supercluster

We present GyVe, an interactive visualization tool for understanding structure in sparse three-dimensional (3D) point data. The scientific goal driving the tool's development is to determine the presence of filaments and voids as defined by inferred 3D galaxy positions within the Horologium-Reticulum supercluster (HRS). GyVe provides visualization techniques tailored to examine structures defined by the intercluster galaxies. Specific techniques include: interactive user control to move between a global overview and local viewpoints, labelled axes and curved drop lines to indicate positions in the astronomical RA-DEC-cz coordinate system, torsional rocking and stereo to enhance 3D perception, and geometrically distinct glyphs to show potential correlation between intercluster galaxies and known clusters. We discuss the rationale for each design decision and review the success of the techniques in accomplishing the scientific goals. In practice, GyVe has been useful for gaining intuition about structures that were difficult to perceive with 2D projection techniques alone. For example, during their initial session with GyVe, our collaborators quickly confirmed scientific conclusions regarding the large-scale structure of the HRS previously obtained over months of study with 2D projections and statistical techniques. Further use of GyVe revealed the spherical shape of voids and showed that a presumed filament was actually two disconnected structures.     

High accuracy FIONA-AFM hybrid imaging

Multi-protein complexes are ubiquitous and play essential roles in many biological mechanisms. Single molecule imaging techniques such as electron microscopy (EM) and atomic force microscopy (AFM) are powerful methods for characterizing the structural properties of multi-protein and multi-protein-DNA complexes. However, a significant limitation to these techniques is the ability to distinguish different proteins from one another. Here, we combine high resolution fluorescence microscopy and AFM (FIONA-AFM) to allow the identification of different proteins in such complexes. Using quantum dots as fiducial markers in addition to fluorescently labeled proteins, we are able to align fluorescence and AFM information to ≥8 nm accuracy. This accuracy is sufficient to identify individual fluorescently labeled proteins in most multi-protein complexes. We investigate the limitations of localization precision and accuracy in fluorescence and AFM images separately and their effects on the overall registration accuracy of FIONA-AFM hybrid images. This combination of the two orthogonal techniques (FIONA and AFM) opens a wide spectrum of possible applications to the study of protein interactions, because AFM can yield high resolution (5-10 nm) information about the conformational properties of multi-protein complexes and the fluorescence can indicate spatial relationships of the proteins in the complexes.     

Effects of Pore Geometry on the Fatigue Properties of Electron Beam Melted Titanium-6Al-4V

Current percent-porosity based quantification of pores in additively manufactured parts does not provide information about the size, shape, and distribution of pores throughout a build. Such information is necessary to understand the conditions under which the part was printed as well as its mechanical reliability. This research, through a combination of fatigue testing and microstructural characterization demonstrates a method by which the internal porosity can be characterized and using the knowledge of the pores differing formation mechanisms to inform future design and build strategies. Though the test bars were printed under nominally identical conditions, ignoring lack-of-fusion, batch 1 had 34 pct fewer lenticular pores and 147 pct more spherical pores than batch 2 which shows that the actual print conditions of these parts varied substantially as would their as-printed mechanical reliability. To quantify this difference extensive optical, SEM, and EBSD metallographic studies were conducted on several samples from these bars as well as the fracture surfaces to gain an understanding of the porosity’s shape, size, and location. The comparison of these datasets along with knowledge of the pore’s evolution allows for the optimization of future build strategies and the more accurate prediction of the resulting as-built mechanical properties.