Creativity, Discovery, Engagement
Learning Like No Other
Stay up-to-date on the latest research and build relationships with academics at the Materials Science & Biophysics Seminar Series, which bring experts from around the world to campus to discuss their recent findings. Everyone is welcome!
 F. Levent Degertekin, PhD, George W. Woodruff Chair in Mechanical Systems and Professor
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Microscale Ultrasonic and Acousto-optical Sensors and Systems for Medical ImagingFriday, March 15, 2024 Health Sciences Building EC 1218 2:00 - 3:00 PM Host: Dr. Mustafa Culha (mculha@augusta.edu) Microscale sensors and systems are important components for medical imaging especially for minimally invasive procedures such as interventions in coronary arteries and structural heart procedures where the size of device determines the reach of the imaging modality in the body. Based on silicon micromachining technology, capacitive micromachined ultrasonic transducers (CMUTs) have found their place in medical ultrasound imaging mostly due to the advantages in electronics integration for large 2D arrays and miniaturized systems for catheter-based intravascular ultrasound (IVUS) imaging. In this talk, we will first discuss our work on high frequency CMUT-on-CMOS IVUS devices operating in the 20-50MHz range including forward looking volumetric imaging in the arteries as well as systems that can be used over 0.014” coronary guidewires. In the second half of the talk, we will describe an acousto-optical RF field sensor for magnetic resonance imaging (MRI) which uses a piezoelectric transducer coupled to an optical fiber to measure the local electromagnetic field. Since the signal is carried out on a dielectric medium, this approach is MRI safe in terms of RF induced heating and does not introduce image artifacts. We demonstrate this sensor as an active marker to track catheter position for structural heart interventions in animal studies as well as its use as an MRI safety sensor by mapping E-field variations around metallic implants in phantom studies. We end the talk with future directions we envision for these technologies. |
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Ultrafast Atom Dynamics + Magnetism in Low DimensionsFriday, March 29, 2024 Health Sciences Building EC 1218 2:00 - 3:00 PM Host: Dr. Trinanjan Datta (tdatta@augusta.edu) A revolution in materials physics is currently underway caused by efforts to explain the wide range of phenomena that have been uncovered in low-dimensional (low-D) van der Waals crystals. The production of graphene-inspired materials has led to a huge number of discoveries in fundamental condensed matter science. In fact, our theoretical understanding of electron physics in 2 dimensions has been constantly re-adjusted as topological behaviors are found to be applicable. In the midst of this intellectual shift, quests to observe magnetism in 2D, graphene-like materials were launched; the result was the identification of magnetic order in low-D, chromium-based van der Waals crystals in 2017. We have explored such a 2D magnet CrSBr. It is a highly versatile, technologically promising material with many exciting properties due to the strong coupling between magnetism, lattice deformation and charge arrangement. Ultrafast atomic dynamics have been observed to be intimately coupled to the magnetic ordering state. Femtosecond pump-probe experiments reveal that the coherent motion of atoms is affected by the presence of antiferromagnetism. The collective atomic motion turns out to be coherent acoustic phonons (elastic waves) that mediate apparent structural deformations in the 2D magnetic crystal. We propose that CrSBr magnetic ordering can influence the collective motion of atoms on an ultrafast time scale. Further, CrSBr may provide an example of a system in which non-equilibrium-induced acoustic phonons may be protected in close analogy with modes in 2D electron systems. These results are germane to the field of strongly correlated electron systems (SCES) as CrSBr exhibits delicate couplings between different quantum sectors. The results will also be of relevance to the important problem of ultrafast demagnetization. And the findings exemplify an emerging field termed strongly correlated electron-photon systems (SCPS). The talk will place the results within the context of these three areas while discussing the search for exotic phonon behavior suggested by the experiments. |
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Persistent Micelle Templates for Single-Variable Series of Porous NanomaterialsFriday, April 19, 2024 Health Sciences Building EC 1218 2:00 - 3:00 PM Host: Dr. Mustafa Culha (mculha@augusta.edu) Block polymer structure‐directing agents (SDA) enable the production of porous nanoscale materials by controlling the arrangement of material precursors. The subsequent removal of the polymer thus yields porous nanomaterials that are useful for a wide range of applications including energy storage and catalysis. The iteration of most such strategies however lead to complex sequences of nanomaterials that change multiple spatial variables at a time, including morphology, pore size, and wall thickness due to equilibration. In contrast, persistent micelle templates (PMT) are based upon the kinetic entrapment of polymer chains to enable sample adjustments with constant morphology (isomorphic) and constant pore size. Such series of nanomaterials with a single spatial variable are well poised to clarify cause-and-effect for nanoscale phenomena. The PMT approach has enabled wide spanning feature sizes over two orders of magnitude with 2 Å precision adjustments between samples. The PMT method is simple to validate with diffraction models and is feasible in any laboratory with minimal equipment. Finally, recent energy device research enabled by PMT are noted where tailored nanomaterials provided a unique perspective to unravel complex battery behaviors. |
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Coordinating Adhesion with Repulsion: How Cells Use Polymer Brushes to Orchestrate LifeFriday, April 26, 2024 Health Sciences Building EC 1218 2:00-3:00 PM Host: Dr. Abdul Malmi-Kakkada (amalmikakkada@augusta.edu) Multi-cellular organisms rely on reversible adhesions to orchestrate the motion and organization of cells. To date, the physics of tissue formation and cohesion has primarily focused on the molecular adhesions between cells and the balance of forces throughout the tissue. In this talk, I will introduce an important but neglected physical mechanism that cells may use to break or weaken cellular adhesions in a controllable, dynamic fashion. At the heart of this control is cells’ ability to rapidly extrude giant sugar polymers to form a polymer brush-like structure at cell interfaces. I will present data confirming that the repulsive forces generated by this compressed brush (glycocalyx) substantially modify the adhesive state of cells. Further, I will share how our lab has hijacked the cell’s method for tailoring its interface to generate a novel class of ultra-thick polymer brush. We employ these tunable brushes as a biomimetic system to systematically explore the forces exerted by glycocalyx on adherent cells. Experiments confirm that the polymer-generating enzyme, hyaluronan synthase, can squeeze polymers into tight confined spaces and drive dramatic cell deformation or even force cells to detach from the substrate. In light of the observed upregulation of hyaluronan glycocalyx synthesis in biological events that require adhesion modulation, ranging from embryogenesis to synaptogenesis, I argue that controlled growth and organization of large hyaluronan polymers at the cell’s interface may play a substantial role in the mechanics and dynamics of cell organization in multi-cellular systems. |
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Seminar series sponsored by: Augusta University Research Institute, College of Science and Mathematics, Department of Physics and Biophysics
