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4 results on '"WINDLE, AH"'

1. Triboluminescence flashes from high-speed ruptures in carbon nanotube Macro-Yarns

Author

Thurid Gspann, Ngern, Nhh, Fowler, A., Windle, Ah, Tan, Vbc, Elliott, James, Gspann, TS [0000-0002-5750-5275], and Apollo - University of Cambridge Repository

Subjects
Failure mode, Strain rate effect, Triboluminescence, Carbon nanotube, Yarn structure
Abstract

© 2017 During tensile tests of carbon nanotube (CNT) macrostructures (ribbons, ropes and tows) under dynamic strain rates (1000 s –1 ), we recorded temporally sporadic, spatially localized visible light emissions (“flashes”) of less than 1.5 µs duration. The flashes occurred at the fracture sites and were, depending on the sample morphology, either distributed randomly over time (for tows) or occurred all at once over larger areas of several pixels (for ribbons). In situ thermal camera measurements, as well as ex situ analysis by electron microscopy reveal a hierarchical mechanism of overall heating over the whole sample length during straining, and localized heating around the fracture surfaces. Temperatures around the fracture tip were calculated to be of 1800 K in average. We propose that the flashes are caused by charge separation due to CNT bond fracture and gas discharge of the surrounding gases. Triboluminescence, known for larger sugar crystals, has not been observed for carbon nanotubes previously. It results from the yarn-like morphology, the ultra-high strength and thermal conductivity of our CNT fibers, which at high strain rates concentrate the strain at CNT level and lead to CNT fracture, rather than bundle sliding.

Published
2018

4. Multi-walled carbon nanotube induced frustrated phagocytosis, cytotoxicity and pro-inflammatory conditions in macrophages are length dependent and greater than that of asbestos.

Author

Boyles MS, Young L, Brown DM, MacCalman L, Cowie H, Moisala A, Smail F, Smith PJ, Proudfoot L, Windle AH, and Stone V

Subjects
Animals, Asbestos, Amosite toxicity, Bronchoalveolar Lavage Fluid cytology, Cell Line, Cell Survival drug effects, Cells, Cultured, Chemokine CCL2 metabolism, Humans, Iron analysis, Macrophages metabolism, Macrophages physiology, Male, Mice, Nanotubes, Carbon chemistry, Particle Size, Phagocytosis drug effects, Rats, Sprague-Dawley, Soot toxicity, Transforming Growth Factor beta1 metabolism, Tumor Necrosis Factor-alpha metabolism, Macrophages drug effects, Nanotubes, Carbon toxicity
Abstract

The potential toxicity of carbon nanotubes (CNTs) has been compared to pathogenic fibres such as asbestos. It is important to test this hypothesis to ascertain safe methods for CNT production, handling and disposal. In this study aspects reported to contribute to CNT toxicity were assessed: length, aspect ratio, iron content and crystallinity; with responses compared to industrially produced MWCNTs and toxicologically relevant materials such as asbestos. The impacts of these particles on a range of macrophage models in vitro were assessed due to the key role of macrophages in particle clearance and particle/fibre-induced disease. Industrially produced and long MWCNTs were cytotoxic to cells, and were potent in inducing pro-inflammatory and pro-fibrotic immune responses. Short CNTs did not induce any cytotoxicity. Frustrated phagocytosis was most evident in response to long CNTs, as was respiratory burst and reduction in phagocytic ability. Short CNTs, metal content and crystallinity had less or no influence on these endpoints, suggesting that many responses were fibre-length dependent. This study demonstrates that CNTs are potentially pathogenic, as they were routinely found to induce detrimental responses in macrophages greater than those induced by asbestos at the same mass-based dose., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Published
2015
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