Bio Focus: Skin cancer probe applied to in-depth artwork investigation
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Bio Focus Skin cancer probe applied to in-depth artwork investigation
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few years ago, W.S. Warren of Duke University (Durham, N.C.) saw an exhibit at the National Gallery in London on scientific methods for detecting art forgeries. “I walked through that exhibit, and at the end of that time realized that the technologies that were being used were the technologies of 30 to 40 years ago. And asked what would happen if we started using modern bioimaging technologies in this particular application,” Warren said. Warren’s group at Duke University works on biomedical imaging techniques, where they have applied the pump-probe microscopy technique to provide highresolution images of biological pigments in skin cancer research. Pump-probe microscopy is a nonlinear technique in which the signal intensity is proportional to the product of the intensities of two lasers, and less affected by light scattering. Using nearinfrared wavelengths, skin can be probed to ~1 cm depth. As reported in the February 4 issue of PNAS (DOI: 10.1073/pnas.1317230111; p. 1708), Tana Villafana demonstrated the feasibility of the pump-probe microscopy technique to detect forged paintings using mock paintings; this technique was used to investigate specific pigments in a 14th-century painting. Villafana
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MRS BULLETIN
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VOLUME 39 • MAY 2014
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Maxime Matras at FSU started reacting round, 0.8-mm-diameter Ag wires embedded with 666 Bi-2212 powder filaments, each 15 μm in diameter. Inserting this wire into an overpressure furnace at pressures of 1–100 bars during the heat-treating process prevented wire diameter expansion by Ag creep, allowing for the first full densification of the Bi-2212 phase. Measurement of the whole-conductor (or engineering) current density, JE, revealed that JE increased by a factor of eight going from 1 bar to 100 bars pressure. The overpressure collapsed bubbles as they formed, leading to higher critical current density. The research team made a test coil
that reached 33.8 T. Larbalestier said, “This is not just a breakthrough result for short wire samples—it’s a breakthrough using long samples that have been tested in a very high field magnet. The wires are now being scaled up to kilometer lengths with the wire producer, Oxford Superconducting Technology.” The research team wants to repeat this process in YBCO next which, they said, would be genuinely revolutionary for superconducting magnet technology because it would allow construction of multi-Tesla magnets in the 30–70 K regime where no other superconductor can operate. Tim Palucka
is a graduate student in Warren’s team and worked in collaboration with the North Carolina Museum of Art and the Washington National Gallery of Art. There is actually a great deal of similarity between imaging skin and imaging a painting. Warren said, “There are many layers of painting and the layers are designed to replicate the refraction and scattering that you have at normal skin; that’s what makes it look realistic. For example, Da Vinci, when he painted the Mona Lisa, put 40 lay
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