ABSTRACT
Ti3[Al1-δCuδ]C2 MAX phase solid solutions have been synthesized by sintering compacted Ti3AlC2-Cu composites produced by mechanical milling. Using X-ray and neutron diffraction techniques, it is demonstrated that the Cu mixing into the Al site is accompanied by lattice distortion, which leads to symmetry reduction from a hexagonal to a monoclinic structure. Such symmetry reduction likely results from this mixing through deviation of the A-site position from the special (0, 0, 1/4) position within the P63/mmc space group of the original Ti3AlC2 structure. Moreover, it is demonstrated that the Cu admixture into the A site can be adjusted from the composition of the reactant mixture. The lattice parameter variation of the solid solution compounds, with 10-50 atom % Cu in the A site, is found to be consistent with Vegard's law.
ABSTRACT
With the increasing use of optical coherence tomography (OCT) in biomedical applications, robust yet simple methods for calibrating and benchmarking a system are needed. We present here a procedure based on a calibration object complemented with an algorithm that analyzes three-dimensional OCT datasets to retrieve key characteristics of an OCT system. The calibration object combines state-of-the-art tissue phantom material with a diamond-turned aluminum multisegment mirror. This method is capable of determining rapidly volumetric field-of-view, axial resolution, and image curvature. Moreover, as the phantom material mimics biological tissue, the system's signal and noise levels can be evaluated in conditions close to biological experiments. We believe this method could improve OCT quantitative data analysis and help OCT data comparison for longitudinal or multicenter studies.
Subject(s)
Image Processing, Computer-Assisted/methods , Tomography, Optical Coherence/methods , Algorithms , Aluminum/chemistry , Automation , Calibration , Equipment Design , Pattern Recognition, Automated , Phantoms, Imaging , Signal Processing, Computer-Assisted , Signal-To-Noise Ratio , SoftwareABSTRACT
Proof of concept results are presented towards an in situ bimodal proximity sensor for neurovascular bundle detection during dental implant surgery using combined near infrared absorption (NIR) and optical coherence tomography (OCT) techniques. These modalities are shown to have different sensitivity to the proximity of optical contrast from neurovascular bundles. NIR AC and DC signals from the pulsing of an artery enable qualitative ranging of the bundle in the millimeter range, with best sensitivity around 0.5-3mm distance in a custom phantom setup. OCT provides structural mapping of the neurovascular bundle at sub-millimeter distances in an ex vivo human jaw bone. Combining the two techniques suggests a novel ranging system for the surgeon that could be implemented in a "smart drill." The proximity to the neurovascular bundle can be tracked in real time in the range of a few millimeters with NIR signals, after which higher resolution imaging OCT to provide finer ranging in the sub-millimeter distances.
