ORCID Profile
0000-0001-8562-0353
Current Organisations
Northwestern University
,
Argonne National Laboratory
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Publisher: Proceedings of the National Academy of Sciences
Date: 09-02-2015
Abstract: X-ray fluorescence microscopy provides unparalleled sensitivity for measuring the distribution of trace elements in many-micrometer-thick specimens, whereas ptychography offers a path to the imaging of weakly fluorescing biological ultrastructure at beyond-focusing-optic resolution. We demonstrate here for the first time, to our knowledge, the combination of fluorescence and ptychography for imaging frozen-hydrated specimens at cryogenic temperatures, with excellent structural and chemical preservation. This combined approach will have significant impact on studies of the intracellular localization of nanocomposites with attached therapeutic or diagnostic agents, help elucidate the roles of trace metals in cell development, and further the study of diseases where trace metal misregulation is suspected (including neurodegenerative diseases).
Publisher: The Optical Society
Date: 23-02-2015
DOI: 10.1364/OE.23.005438
Publisher: International Union of Crystallography (IUCr)
Date: 27-08-2014
DOI: 10.1107/S160057751401621X
Abstract: X-ray nanoprobes require coherent illumination to achieve optic-limited resolution, and so will benefit directly from diffraction-limited storage rings. Here, the ex le of high-resolution X-ray fluorescence tomography is focused on as one of the most voracious demanders of coherent photons, since the detected signal is only a small fraction of the incident flux. Alternative schemes are considered for beam delivery, s le scanning and detectors. One must consider as well the steps before and after the X-ray experiment: s le preparation and examination conditions, and analysis complexity due to minimum dose requirements and self-absorption. By understanding the requirements and opportunities for nanoscale fluorescence tomography, one gains insight into the R& D challenges in optics and instrumentation needed to fully exploit the source advances that diffraction-limited storage rings offer.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-12-2006
Abstract: The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these s les shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.
Location: United States of America
No related grants have been discovered for Chris Jacobsen.