Prof. Jacobsen's group develops novel methods, instruments, and analysis approaches for X-ray nanoscale imaging and applies them to biology and environmental science, using the Advanced Photon Source (APS) at Argonne. Directions: (1) Scanning X-ray fluorescence microscopy (SXFM) for organ-wide and nanoscale elemental mapping of metals (zinc, copper, iron) in biological tissues — central to the NIH-funded QE-Map national resource; imaging how metals regulate cellular functions, synaptic zinc signaling, and neurodegenerative disease; (2) X-ray ptychography and coherent diffractive imaging (CDI) for nanoscale biological imaging beyond the diffraction limit with improved dose efficiency; (3) Development of new algorithms, optics (zone plates), and detector systems to push spatial resolution and dose efficiency in X-ray microscopy — including lensless imaging methods and compressed-sensing reconstruction. Joint appointment at Argonne National Laboratory (Argonne Distinguished Fellow); also involved in QE-Map resource with Kozorovitskiy and Hao Zhang (McCormick).