Ecomorphology of the pectoral girdle in anurans (Amphibia, Anura): Shape diversity and biomechanical considerations.

Frogs and toads (Lissamphibia: Anura) show a diversity of locomotor modes that allow them to inhabit a wide range of habitats. The different locomotor modes are likely to be linked to anatomical specializations of the skeleton within the typical frog Bauplan. While such anatomical adaptations of the hind limbs and the pelvic girdle are comparably well understood, the pectoral girdle received much less attention in the past.

Measurement error in μCT-based three-dimensional geometric morphometrics introduced by surface generation and landmark data acquisition.

Computed-tomography-derived (CT-derived) polymesh surfaces are widely used in geometric morphometric studies. This approach is inevitably associated with decisions on scanning parameters, resolution, and segmentation strategies. Although the underlying processing steps have been shown to potentially contribute artefactual variance to three-dimensional landmark coordinates, their effects on measurement error have rarely been assessed systematically in CT-based geometric morphometric studies.

Standard method for microCT-based additive manufacturing quality control 4: Metal powder analysis.

X-ray micro computed tomography (microCT) can be applied to analyse powder feedstock used in additive manufacturing. In this paper, we demonstrate a dedicated workflow for this analysis method, specifically for Ti6Al4V powder typically used in commercial powder bed fusion (PBF) additive manufacturing (AM) systems. The methodology presented includes sample size requirements, scan conditions and settings, reconstruction and image analysis procedures.

Standard method for microCT-based additive manufacturing quality control 2: Density measurement.

MicroCT is best known for its ability to detect and quantify porosity or defects, and to visualize its 3D distribution. However, it is also possible to obtain accurate volumetric measurements from parts - this can be used in combination with the part mass to provide a good measure of its average density. The advantage of this density-measurement method is the ability to combine the density measurement with visualization and other microCT analyses of the same sample.

Standard method for microCT-based additive manufacturing quality control 3: Surface roughness.

The use of microCT of 10 mm coupon samples produced by AM has the potential to provide useful information of mean density and detailed porosity information of the interior of the samples. In addition, the same scan data can be used to provide surface roughness analysis of the as-built surfaces of the same coupon samples. This can be used to compare process parameters or new materials.

Standard method for microCT-based additive manufacturing quality control 1: Porosity analysis.

MicroCT is a well-established technique that is used to analyze the interior of objects non-destructively, and it is especially useful for void or porosity analysis. Besides its widespread use, few standards exist and none for additive manufacturing as yet. This is due to the inherent differences in part design, sizes and geometries, which results in different scan resolutions and qualities.

Use of Isotope-Edited FTIR to Derive a Backbone Structure of a Transmembrane Protein.

Solving structures of membrane proteins has always been a formidable challenge, yet even upon success, the results are normally obtained in a mimetic environment that can be substantially different from a biological membrane. Herein, we use noninvasive isotope-edited FTIR spectroscopy to derive a structural model for the SARS coronavirus E protein transmembrane domain in lipid bilayers. Molecular-dynamics-based structural refinement, incorporating the IR-derived orientational restraints points to the formation of a helical hairpin structure.

Temperature-dependent in-plane structure formation of an X-shaped bolapolyphile within lipid bilayers.

Polyphilic compound B12 is an X-shaped molecule with a stiff aromatic core, flexible aliphatic side chains, and hydrophilic end groups. Forming a thermotropic triangular honeycomb phase in the bulk between 177 and 182 °C but no lyotropic phases, it is designed to fit into DPPC or DMPC lipid bilayers, in which it phase separates at room temperature, as observed in giant unilamellar vesicles (GUVs) by fluorescence microscopy. TEM investigations of bilayer aggregates support the incorporation of B12 into intact membranes.

Peptide model helices in lipid membranes: insertion, positioning, and lipid response on aggregation studied by X-ray scattering.

Studying membrane active peptides or protein fragments within the lipid bilayer environment is particularly challenging in the case of synthetically modified, labeled, artificial, or recently discovered native structures. For such samples the localization and orientation of the molecular species or probe within the lipid bilayer environment is the focus of research prior to an evaluation of their dynamic or mechanistic behavior. X-ray scattering is a powerful method to study peptide/lipid interactions in the fluid, fully hydrated state of a lipid bilayer.

A novel heavy-atom label for side-specific peptide iodination: synthesis, membrane incorporation and X-ray reflectivity.

Structural parameters, such as conformation, orientation and penetration depth of membrane-bound peptides and proteins that may function as channels, pores or biocatalysts, are of persistent interest and have to be probed in the native fluid state of a membrane. X-ray scattering in combination with heavy-atom labeling is a powerful and highly appropriate method to reveal the position of a certain amino acid residue within a lipid bilayer with respect to the membrane normal axis up to a resolution of several Angstrøm. Herein, we report the synthesis of a new iodine-labeled amino acid building block.

X-ray structure analysis of free-standing lipid membranes facilitated by micromachined apertures.

Silicon and Teflon substrates have been structured by wet etching and a focused ion beam (FIB) to obtain very defined, clean apertures. Planar, free-standing lipid membranes (black lipid membranes (BLM)) with enhanced long-term stability have been prepared on these apertures by the methods of Montal and Müller(1,2) as well as Müller and Rudin.(3) The stability and geometric control enables the use of X-ray analysis of free-standing single bilayers.