Dataset Information

Stable Speckle Patterns for Nano-scale Strain Mapping up to 700 °C.

ABSTRACT: The digital image correlation (DIC) of speckle patterns obtained by vapour-assisted gold remodelling at 200 - 350 °C has already been used to map plastic strains with submicron resolution. However, it has not so far proved possible to use such patterns for testing at high temperatures. Here we demonstrate how a gold speckle pattern can be made that is stable at 700 °C, to study deformation in a commercial TiAl alloy (Ti-45Al-2Nb-2Mn(at%)-0.8 vol% TiB2). The pattern is made up of a uniformly sized random array of Au islands as small as 15 nm in diameter, depending on reconstruction parameters, with a sufficiently small spacing to be suitable for nano-scale, nDIC, strain mapping at a subset size of 60 × 60 nm2. It can be used at temperatures up to 700 °C for many hours, for high cycle fatigue testing for instance. There is good particle attachment to the substrate. It can withstand ultra-sound cleaning, is thermally stable and has a high atomic number contrast for topography-free backscatter electron imaging.

SUBMITTER: Edwards TEJ

PROVIDER: S-EPMC6407731 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Stable Speckle Patterns for Nano-scale Strain Mapping up to 700 °C.

Edwards T E J TEJ Di Gioacchino F F Springbett H P HP Oliver R A RA Clegg W J WJ

Experimental mechanics 20170728 9

The digital image correlation (DIC) of speckle patterns obtained by vapour-assisted gold remodelling at 200 - 350 °C has already been used to map plastic strains with submicron resolution. However, it has not so far proved possible to use such patterns for testing at high temperatures. Here we demonstrate how a gold speckle pattern can be made that is stable at 700 °C, to study deformation in a commercial TiAl alloy (Ti-45Al-2Nb-2Mn(at%)-0.8 vol% TiB<sub>2</sub>). The pattern is made up of a uni ...[more]

PMID: 30930472

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Project description:Patients with acute coronary artery disease (CAD) exhibit reduced global and regional strain and strain rate (S/SR). However, knowledge about segmental S/SR in stable CAD patients is still limited. This study aimed to investigate whether resting segmental S/SR measurements differ in patients with chronic chest pain who have normal coronary arteries or stenotic coronary arteries, and to compare these measurements to those in patients with revascularized myocardial infarction (MI). We prospectively enrolled 510 patients with chronic chest pain referred for coronary computed tomography angiography (CCTA) and 102 patients revascularized after MI. All participants underwent transthoracic echocardiography featuring S/SR analysis. In addition to the patients with MI, patients with suspected CAD based on CCTA findings subsequently underwent invasive coronary angiography (CAG). We assessed global longitudinal strain (GLS) and averaged segmental peak longitudinal strain during systole (PLS), peak systolic strain rate (SRs), peak early diastolic strain rate (SRe), and post systolic shortening (PSS). We also determined functionally reduced segment percentages using differing S/SR cut-off values. There were significant disparities in all average segmental S/SR metrics between the No-CAD and MI groups. SRe was the only S/SR metric that differed significantly between the No-CAD and PCI groups. Differences in SRe, PLS and GLS measurements were observed between the No-CAD and CABG groups. The proportion of diminished segmental S/SR mirrored these findings. For the percentage of pathological segments with varying cut-off values, segmental SRe below 1.5 s- 1 displayed the most marked difference among the four groups (p < 0.001). Revascularized MI patients or those referred to CABG present with diminished segmental S/SR values. However, among patients with chronic chest pain, only segmental SRe discerns subtle disparities between the No-CAD and the PCI group. The diagnostic accuracy of SRe warrants further exploration in subsequent studies.

Dataset Information

Stable Speckle Patterns for Nano-scale Strain Mapping up to 700 °C.

Publications

Stable Speckle Patterns for Nano-scale Strain Mapping up to 700 °C.

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