Soft X-ray phase nano-microscopy of micrometre-thick magnets

Imaging of nanoscale magnetic textures within extended material systems is of critical importance both to fundamental research and technological applications. Whilst high resolution magnetic imaging of thin nanoscale samples is well-established with electron and soft X-ray microscopy, the extension to micrometer-thick systems with hard X-rays currently limits high resolution imaging to rare-earth magnets. Here we overcome this limitation by establishing soft X-ray magnetic imaging of micrometer-thick systems using the pre-edge phase X-ray Magnetic Circular Dichroism signal, thus making possible the study of a wide range of magnetic materials. By performing dichroic spectro-ptychography, we demonstrate high spatial resolution imaging of magnetic samples up to 1.7 {\mu}m thick, an order of magnitude higher than conventionally possible with absorption-based techniques. This new regime of magnetic imaging makes possible the study of extended non rare-earth systems that have until now been inaccessible, from magnetic textures for future spintronic applications to non-rare-earth permanent magnets

Nanoscale cuticle density variations correlate with pigmentation and color in butterfly wing scales

How pigment distribution correlates with cuticle density within a microscopic butterfly wing scale, and how both impact final reflected color remains unknown. We used ptychographic X-ray computed tomography to quantitatively determine, at nanoscale resolutions, the three-dimensional mass density of scales with pigmentation differences. By comparing cuticle densities with pigmentation and color within a scale, we determine that the lower lamina structure in all scales has the highest density and lowest pigmentation. Low pigment levels also correlate with sheet-like chitin structures as opposed to rod-like structures, and distinct density layers within the lower lamina help explain reflected color. We propose that pigments, in addition to absorbing specific wavelengths, can affect cuticle polymerization, density, and refractive index, thereby impacting reflected wavelengths that produce structural colors

Electrospray sample injection for single-particle imaging with x-ray lasers

The possibility of imaging single proteins constitutes an exciting challenge for x-ray lasers. Despite encouraging results on large particles, imaging small particles has proven to be difficult for two reasons: not quite high enough pulse intensity from currently available x-ray lasers and, as we demonstrate here, contamination of the aerosolized molecules by nonvolatile contaminants in the solution. The amount of contamination on the sample depends on the initial droplet size during aerosolization. Here, we show that, with our electrospray injector, we can decrease the size of aerosol droplets and demonstrate virtually contaminant-free sample delivery of organelles, small virions, and proteins. The results presented here, together with the increased performance of next-generation x-ray lasers, constitute an important stepping stone toward the ultimate goal of protein structure determination from imaging at room temperature and high temporal resolution. © 2019 The Authors

Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a wellcharacterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 mu m diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 angstrom ngstrom were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.11Ysciescopu

Megahertz single-particle imaging at the European XFEL

The emergence of high repetition-rate X-ray free-electron lasers (XFELs) powered by superconducting accelerator technology enables the measurement of significantly more experimental data per day than was previously possible. The European XFEL is expected to provide 27,000 pulses per second, over two orders of magnitude more than any other XFEL. The increased pulse rate is a key enabling factor for single-particle X-ray diffractive imaging, which relies on averaging the weak diffraction signal from single biological particles. Taking full advantage of this new capability requires that all experimental steps, from sample preparation and delivery to the acquisition of diffraction patterns, are compatible with the increased pulse repetition rate. Here, we show that single-particle imaging can be performed using X-ray pulses at megahertz repetition rates. The results obtained pave the way towards exploiting high repetition-rate X-ray free-electron lasers for single-particle imaging at their full repetition rate.We acknowledge European XFEL in Schenefeld, Germany, for provision of X-ray free-electron laser beamtime at Scientific Instrument SPB/SFX and would like to thank the instrument group and facility staff for their assistance. We acknowledge the use of the XBI biological sample preparation laboratory, enabled by the XBI User Consortium. The results of the work were obtained using Maxwell computational resources operated at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany, and computational resources of MCC NRC “Kurchatov Institute.” This research used resources of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. We acknowledge the support of funding from: the Swedish Foundation for International Cooperation in Research and Higher Education (STINT); Helmholtz Associations Initiative and Networking Fund and the Russian Science Foundation grant HRSF-0002/18-41-0600; the Russian Science Foundation grant 18-14-00321; European Research Council, “Frontiers in Attosecond X-ray Science: Imaging and Spectroscopy (AXSIS),” ERC-2013-SyG 609920; Fellowship from the Joachim Herz Stiftung; Singapore National Research Foundation Grant number NRF-CRP16-2015-05; Ministry of Education, Science, Research and Sport of the Slovak Republic and by grant APVV-18-0104; the project CZ.02.1.01/0.0/0.0/16_019/0000789 (ADONIS) from European Regional Development Fund, Chalmers Area of Advance; Material Science and the Ministry of Education, Youth and Sports as part of targeted support from the National Programme of Sustainability II; US National Science Foundation (NSF) Science and Technology Center BioXFEL Award 1231306; Helmholtz Initiative and Networking Fund through the Young Investigators Group Program and Deutsche Forschungsgemeinschaft, project B03/SFB755; VR starting grant (2018-03387); FORMAS future research leader (2018-00421); KVA Biosciences 2018 (BS2018-0053); NSF 1231306; German Ministry for Education and Research, BMBF (grant No. 05K2016—Visavix); the Heinrich Pette Institute, Leibniz Institute for Experimental Virology is supported by the Free and Hanseatic City of Hamburg and the Federal Ministry of Health; NSF STC BioXFEL grant 1231306; The National Research Foundation (NRF) of Korea (Grant No. 2017K1A3A7A09016380); the Röntgen-Ångström Cluster; the Swedish Research Council; the Swedish Foundation for Strategic Research. We thank Arwen Pearson for critical reading of the manuscript. Open access funding provided by Uppsala University

Intergenerational impacts of maternal mortality: Qualitative findings from rural Malawi

Background: Maternal mortality, although largely preventable, remains unacceptably high in developing countries such as Malawi and creates a number of intergenerational impacts. Few studies have investigated the far-reaching impacts of maternal death beyond infant survival. This study demonstrates the short- and long-term impacts of maternal death on children, families, and the community in order to raise awareness of the true costs of maternal mortality and poor maternal health care in Neno, a rural and remote district in Malawi. Methods: Qualitative in-depth interviews were conducted to assess the impact of maternal mortality on child, family, and community well-being. We conducted 20 key informant interviews, 20 stakeholder interviews, and six sex-stratified focus group discussions in the seven health centers that cover the district. Transcripts were translated, coded, and analyzed in NVivo 10. Results: Participants noted a number of far-reaching impacts on orphaned children, their new caretakers, and extended families following a maternal death. Female relatives typically took on caregiving responsibilities for orphaned children, regardless of the accompanying financial hardship and frequent lack of familial or governmental support. Maternal death exacerbated children’s vulnerabilities to long-term health and social impacts related to nutrition, education, employment, early partnership, pregnancy, and caretaking. Impacts were particularly salient for female children who were often forced to take on the majority of the household responsibilities. Participants cited a number of barriers to accessing quality child health care or support services, and many were unaware of programming available to assist them in raising orphaned children or how to access these services. Conclusions: In order to both reduce preventable maternal mortality and diminish the impacts on children, extended families, and communities, our findings highlight the importance of financing and implementing universal access to emergency obstetric and neonatal care, and contraception, as well as social protection programs, including among remote populations

Coherent soft X-ray diffraction imaging of coliphage PR772 at the Linac coherent light source

Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source. The diameter of PR772 ranges from 65–70 nm, which is considerably smaller than the previously reported ~600 nm diameter Mimivirus. This reflects continued progress in XFEL-based single-particle imaging towards the single molecular imaging regime. The data set contains significantly more single particle hits than collected in previous experiments, enabling the development of improved statistical analysis, reconstruction algorithms, and quantitative metrics to determine resolution and self-consistency