Bio

Leora is an Assistant Professor in the Department of Materials Science & Engineering, with a courtesy appointment in Mechanical Engineering, a term appointment in Photon Science at the SLAC National Accelerator Lab, and an appointment as a Precourt Center Fellow. Before coming to Stanford, Leora was a Lawrence Fellow in the Physics Division of the Physics and Life Sciences Directorate at Lawrence Livermore National Labs, where she developed the tools to study time-resolved defect dynamics in bulk materials -- giving new insights into long-standing problems in materials science. She led a large collaboration towards these goals and was involved in many projects that used dark-field X-ray microscopy and other tools to study dislocation patterning, recovery in metals, ultrahigh strength materials, radiation damage, automation and shape recognition methods. Leora did her PhD in Physical Chemistry with Prof. Keith Nelson at MIT, where she demonstrated how shock waves initiate chemistry in RDX that couples to deformations in unique ways that enhance the sensitivity. During that work, she also developing the ultrafast microscope for the study, which took movies with 300 billion frames per second of how quasi-2D shock waves converge, and adapted computer vision methods to quantify the imaging results. Leora did her BA and MSc in Chemistry at the University of Pennsylvania.

Academic Appointments

Administrative Appointments

  • Gabilan Fellow, Stanford University (2021 - Present)
  • Terman Fellow, School of Engineering, Stanford (2021 - Present)
  • Courtesy Appointment, Mechanical Engineering, Stanford (2021 - Present)
  • Precourt Center Fellow, Precourt Center for Renewable Energy, Stanford (2021 - Present)
  • Term Appointment, Photon Science, SLAC (2021 - Present)

Contact

  • Academic
    leoradm@stanford.edu
    University - Faculty Department: Materials Science and Engineering Position: Asst Professor
    • 476 LOMITA MALL
    • STANFORD,  California  94305 

Additional Info

Links

Current Research and Scholarly Interests

My group develops new optical and analytical tools to reveal how imperfections deep inside materials instigate the dynamics that transform them. Spanning length- and time-scales from bonds breaking at single atoms through fracture or fatigue in macroscopic materials, these defect dynamics define complex high-dimensional problems that are difficult to reconcile at intermediate scales in order to predict or understand a material's behavior. To address this challenge, my group develops new types of time-resolved experiments aimed at the elusive "mesoscale" to directly visualize how large populations of subsurface defects drive them. With these new approaches, we tackle fundamental studies of how temperature drives materials, and more applied problems that connect our new insights to structural materials, manufacturing, energy science, and beyond.

2022-23 Courses

Stanford Advisees

All Publications

  • An automated approach to the alignment of compound refractive lenses JOURNAL OF SYNCHROTRON RADIATION Breckling, S., Kozioziemski, B., Dresselhaus-Marais, L., Gonzalez, A., Williams, A., Simons, H., Chow, P., Howard, M. 2022; 29: 947-956

    Abstract

    Compound refractive lenses (CRLs) are established X-ray focusing optics, and are used to focus the beam or image the sample in many beamlines at X-ray facilities. While CRLs are quite established, the stack of single lens elements affords a very small numerical aperture because of the thick lens profile, making them far more difficult to align than classical optical lenses that obey the thin-lens approximation. This means that the alignment must be very precise and is highly sensitive to changes to the incident beam, often requiring regular readjustments. Some groups circumvent the full realignment procedure by using engineering controls (e.g. mounting optics) that sacrifice some of the beam's focusing precision, i.e. spot size, or resolution. While these choices minimize setup time, there are clear disadvantages. This work presents a new automated approach to align CRLs using a simple alignment apparatus that is easy to adapt and install at different types of X-ray experiments or facilities. This approach builds on recent CRL modeling efforts, using an approach based on the Stochastic Nelder-Mead (SNM) simplex method. This method is outlined and its efficacy is demonstrated with numerical simulation that is tested in real experiments conducted at the Advanced Photon Source to confirm its performance with a synchrotron beam. This work provides an opportunity to automate key instrumentation at X-ray facilities.

    View details for DOI 10.1107/S1600577522004039

    View details for Web of Science ID 000824201700003

    View details for PubMedID 35787560

    View details for PubMedCentralID PMC9255570

  • X-ray free-electron laser based dark-field X-ray microscopy: a simulation-based study JOURNAL OF APPLIED CRYSTALLOGRAPHY Holstad, T., Raeder, T., Carlsen, M., Knudsen, E., Dresselhaus-Marais, L., Haldrup, K., Simons, H., Nielsen, M., Poulsen, H. 2022; 55: 112-121

    View details for DOI 10.1107/S1600576721012760

    View details for Web of Science ID 000749998900012

  • In situ visualization of long-range defect interactions at the edge of melting. Science advances Dresselhaus-Marais, L. E., Winther, G., Howard, M., Gonzalez, A., Breckling, S. R., Yildirim, C., Cook, P. K., Kutsal, M., Simons, H., Detlefs, C., Eggert, J. H., Poulsen, H. F. 2021; 7 (29)

    Abstract

    Connecting a bulk material's microscopic defects to its macroscopic properties is an age-old problem in materials science. Long-range interactions between dislocations (line defects) are known to play a key role in how materials deform or melt, but we lack the tools to connect these dynamics to the macroscopic properties. We introduce time-resolved dark-field x-ray microscopy to directly visualize how dislocations move and interact over hundreds of micrometers deep inside bulk aluminum. With real-time movies, we reveal the thermally activated motion and interactions of dislocations that comprise a boundary and show how weakened binding forces destabilize the structure at 99% of the melting temperature. Connecting dynamics of the microstructure to its stability, we provide important opportunities to guide and validate multiscale models that are yet untested.

    View details for DOI 10.1126/sciadv.abe8311

    View details for PubMedID 34261647

https://orcid.org/0000-0002-0757-0159