Wide-field phase imaging for the endoscopic detection of dysplasia and early-stage esophageal cancer

© 2018 SPIE. Esophageal cancer has a 5-year survival rate below 20%, but can be curatively resected if it is detected early. At present, poor contrast for early lesions in white light imaging leads to a high miss rate in standard-of-care endoscopic surveillance. Early lesions in the esophagus, referred to as dysplasia, are characterized by an abundance of abnormal cells with enlarged nuclei. This tissue has a different refractive index profile to healthy tissue, which results in different light scattering properties and provides a source of endogenous contrast that can be exploited for advanced endoscopic imaging. For example, point measurements of such contrast can be made with scattering spectroscopy, while optical coherence tomography generates volumetric data. However, both require specialist interpretation for diagnostic decision making. We propose combining wide-field phase imaging with existing white light endoscopy in order to provide enhanced contrast for dysplasia and early-stage cancer in an image format that is familiar to endoscopists. Wide-field phase imaging in endoscopy can be achieved using coherent illumination combined with phase retrieval algorithms. Here, we present the design and simulation of a benchtop phase imaging system that is compatible with capsule endoscopy. We have undertaken preliminary optical modelling of the phase imaging setup, including aberration correction simulations and an investigation into distinguishing between different tissue phantom scattering coefficients. As our approach is based on phase retrieval rather than interferometry, it is feasible to realize a device with low-cost components for future clinical implementation

Clinically Unapparent Infantile Thiamin Deficiency in Vientiane, Laos

Infantile beriberi, or clinical thiamin (vitamin B1) deficiency in infants, is a forgotten disease in Asia, where 100 years ago it was a major public health problem. Infants with this deficiency, commonly aged ∼ 2–3 months, present in cardiac failure but usually rapidly improve if given thiamin injections. It remains relatively common in Vientiane, Lao PDR (Laos), probably because of prolonged intra- and post-partum food avoidance behaviours. Clinical disease may be the tip of an iceberg with subclinical thiamin deficiency contributing to sickness in infants without overt clinical beriberi. We therefore recruited 778 sick infants admitted during one year at Mahosot Hospital, Vientiane, without clinical evidence of beriberi, and performed erythrocyte transketolase (ETK) assays. 13.4 % of infants had basal ETK<0.59 micromoles/min/gHb suggesting biochemical thiamin deficiency. Mortality was 5.5% but, among infants ≥2 months old, mortality was higher in those with basal ETK<0.59 micromoles/min/gHb (3/47, 6.4%) than in those with basal ETK≥0.59 micromoles/min/gHb (1/146, 0.7%) (P = 0.045, relative risk = 9.32 (95%CI 0.99 to 87.5)). We conclude that clinically unapparent thiamin deficiency is common among sick infants (≥2 months old) admitted to hospital in Vientiane. This may contribute to mortality and a low clinical threshold for providing thiamin to sick infants may be needed

Grain boundary misorientation and thermal grooving in cube-textured Ni and Ni-Cr tape

AFM and EBSD characterization has been carried out to measure the degree of grain boundary grooving in cube-textured Ni and Ni-10wt%Cr substrates. Low angle grain boundary grooves are found to be consistently shallower than grooves at high angle boundaries. Our results suggest that the recrystallization of pure Ni substrates in a Ar-H, atmosphere rather than vacuum may be beneficial in minimizing groove depth. Grain boundary grooves in Ni-10wt%Cr tape were found to be deeper than in pure Ni, consistent with the higher temperature used for recrystallization

Fabrication of biaxially textured Ni substrates and LaNiO3 buffer layers for Tl-1223 thick films

We have fabricated cube texture nickel substrates and examined the relationship between percentage rolling deformation and annealing conditions on the degree of texture obtained using,XRD and EBSD techniques. We have found that unaligned grains may be avoided by rolling to 95% reduction and annealing at 800 degrees C for 4 hours. We have fabricated LaNiO3 films on YSZ and lanthanum aluminate by spray pyrolysis and achieved cube texture in thin coatings

Microstructural studies of Tl2Ba2Ca2Cu3Ox thin films on LaAlO3 and MgO substrates.

Tl(2)Ba2Ca(2)Cu(3)O(x) thin films have been fabricated on (001) LaAlO3 and (001) MgO substrates. Films grown on LaAlO3 have T-c=112K and R-s(80K, 10GHz)=0.2m Ohm, while films on MgO have T-c=117K and R-s(80K; 10GHz)=0.7m Ohm. The grain size and alignment of the Alms has been investigated using X-ray diffraction, Scanning Electron Microscopy and Electron Backscattered Diffraction. We show evidence for a markedly higher in-plane angular spread for films on MgO and believe that for films grown on this substrate the lowest achievable values of R-s are limited by disorder in the in-plane alignment of the TBCCO film caused by the large lattice mismatch between the materials

Wide-field phase imaging for the endoscopic detection of dysplasia and early-stage esophageal cancer

© 2018 SPIE. Esophageal cancer has a 5-year survival rate below 20%, but can be curatively resected if it is detected early. At present, poor contrast for early lesions in white light imaging leads to a high miss rate in standard-of-care endoscopic surveillance. Early lesions in the esophagus, referred to as dysplasia, are characterized by an abundance of abnormal cells with enlarged nuclei. This tissue has a different refractive index profile to healthy tissue, which results in different light scattering properties and provides a source of endogenous contrast that can be exploited for advanced endoscopic imaging. For example, point measurements of such contrast can be made with scattering spectroscopy, while optical coherence tomography generates volumetric data. However, both require specialist interpretation for diagnostic decision making. We propose combining wide-field phase imaging with existing white light endoscopy in order to provide enhanced contrast for dysplasia and early-stage cancer in an image format that is familiar to endoscopists. Wide-field phase imaging in endoscopy can be achieved using coherent illumination combined with phase retrieval algorithms. Here, we present the design and simulation of a benchtop phase imaging system that is compatible with capsule endoscopy. We have undertaken preliminary optical modelling of the phase imaging setup, including aberration correction simulations and an investigation into distinguishing between different tissue phantom scattering coefficients. As our approach is based on phase retrieval rather than interferometry, it is feasible to realize a device with low-cost components for future clinical implementation

The fabrication of Tl-Ba-Ca-Cu-O thin films on SrTiO3 and LaAlO3 buffered MgO substrates for microwave applications.

This paper describes the fabrication of LaAlO3 buffer layers onto (001) MgO, (001) SrTiO3 and SrTiO3-buffered (001) MgO substrates and the subsequent fabrication of Tl-Ba-Ca-Cu-O films onto the buffered substrates. The alignment and the superconducting properties of these films are compared with those of Tl-Ba-Ca-Cu-O films grown by the same process on (001) MgO, (001) LaAlO3, (001) SrTiO3 and SrTiO3-buffered (001) MgO substrates

Robustness to misalignment of low-cost, compact quantitative phase imaging architectures

Non-interferometric approaches to quantitative phase imaging could enable its application in low-cost, miniaturised settings such as capsule endoscopy. We present two possible architectures and both analyse and mitigate the effect of sensor misalignment on phase imaging performance. This is a crucial step towards determining the feasibility of implementing phase imaging in a capsule device. First, we investigate a design based on a folded 4f correlator, both in simulation and experimentally. We demonstrate a novel technique for identifying and compensating for axial misalignment and explore the limits of the approach. Next, we explore the implications of axial and transverse misalignment, and of manufacturing variations on the performance of a phase plate-based architecture, identifying a clear trade-off between phase plate resolution and algorithm convergence time. We conclude that while the phase plate architecture is more robust to misalignment, both architectures merit further development with the goal of realising a low-cost, compact system for applying phase imaging in capsule endoscopy

Control of texture in Ag and Ag-alloy substrates for superconducting tapes

The use of a biaxially textured silver tape as a substrate for high temperature superconductor (HTS) phases is one possible route towards the fabrication of high-Jc superconducting tape. Using a cold-roiling and annealing process we have reproducibly fabricated {110} 〈110〉 textured silver which is stable up to 900 °C. We have found that there are two critical process requirements for the formation of this texture; a low oxygen content in the material prior to deformation, and a cold-rolling thickness reduction of less than 97%. To overcome the problems associated with the poor mechanical strength of pure silver, texture development in Ag-Mg and Ag-Hf alloys with improved mechanical properties has been studied. Heat treatments in a reducing atmosphere allow the {110} 〈110〉 annealing texture to be obtained in Ag-0.1 wt%Mg. The recrystallization behaviour of a Ag-Pd alloy with an increased stacking fault energy was also investigated and a partial cube texture was obtained in this material. Using orientation distribution function (ODF) analysis we have shown that minor variations in the deformation texture of both pure silver and Ag-based alloys can lead to significant differences in the recrystallization textures obtained

Environmentally-assisted grain boundary attack as a mechanism of embrittlement in a nickel-based superalloy

The loss of ductility in the high strength polycrystalline superalloy 720Li is studied in air between room temperature and 1000 °C. Tensile ductility is influenced profoundly by the environment, leading to a pronounced minimum at 750 °C. A relationship between tensile ductility and oxidation kinetics is identified. The physical factors responsible for the ductility dip are established using energy-dispersive X-ray spectroscopy, nanoscale secondary ion mass spectrometry and the analysis of electron backscatter diffraction patterns. Embrittlement results from internal intergranular oxidation along the γ -grain boundaries, and in particular, at incoherent interfaces of the primary γ′ precipitates with the matrix phase. These fail under local microstresses arising from the accumulation of dislocations during slip-assisted grain boundary sliding. Above 850 °C, ductility is restored because the accumulation of dislocations at grain boundaries is no longer prevalent