Conferences, Lectures, & Seminars
Events for June
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Tian Yang Seminar - Friday, June 10th at 2:00pm in EEB 132
Fri, Jun 10, 2016 @ 02:00 PM - 03:00 PM
Ming Hsieh Department of Electrical and Computer Engineering
Conferences, Lectures, & Seminars
Speaker: Tian Yang, Shanghai Jiao Tong University
Talk Title: Nano-plasmonic sensing: single molecule and single chemical event detection, quantum phonon pumping, and fiber end facet integration
Abstract: Nano-plasmonic sensing devices empower the investigation of chemical structures and dynamic behaviors of molecules, reveal fundamental physics at nanometer scales, and provide key components for advanced analytical instruments.
I will start the talk with an introduction to our peculiar surface enhanced Raman spectroscopy (SERS) measurement method, in which a gold nanosphere-plane junction is excited with the focal spot of a radially polarized laser beam. A SERS electromagnetic enhancement factor of 109~10 has been obtained with a reproducibility of 10+/-0.08, in each hotspot of 9 nm3 volume. The unprecedented simultaneous achievement of ultrahigh SERS enhancement and high reproducibility in deterministic single hotspots opens a path for efficient in-situ investigation of single molecule structures and dynamics. For example, several chemical events on the single molecule level have been observed in real time, including plasmon-driven dimerization of 4-nitrobenzenethiol molecules to dimercaptoazobenzene (DMAB), DMAB desorption, and DMAB trans-cis isomer conformation switching, the last of which has been very difficult to observe even for a collection of molecules in any previous experiments. In addition, by measuring the SERS scattering off a monolayer of malachite green isothiocyanate molecules in a single hotspot, we identify a nonlinear dependence of SERS intensity on the laser power, against the common concept that SERS is a linear process. Further, the nonlinear behavior contains multiple heterogeneous stages, which arises from the quantum nature of molecular vibration and stimulated phonon emission.
In the second part of the talk, I shall show our work on integrating nano-plasmonic sensing devices on single-mode optical fiber end facets. Compared with free-space and chip based devices, single-mode fiber end facet devices have the advantages of simple and flexible light delivery, leveraging fiber-optic communication technologies, and compact systems. A plasmonic crystal cavity structure has been designed to improve the refractive index sensing capability under optical fiber guided mode, and a glue-and-strip method has been developed to transfer the plasmonic nano film from a flat substrate to the fiber end facet. A limit of detection of 3.5x10-6 RIU has been obtained, which is two orders of magnitude lower than any reported plasmonic sensors on (multi-mode) fiber end facets. A prototype instrument has been built to demonstrate real-time monitoring of the kinetic interaction process between Human Immunoglobulin G protein (hIgG) and its binding partner anti-hIgG.
Biography: Tian Yang is currently a tenure-track Associate Professor at the University of Michigan - Shanghai Jiao Tong University Joint Institute. He got the B.S. degree in Electrical Engineering from Tsinghua University in 2000, the Ph.D. degree in Electrical Engineering from the University of Southern California in 2006, took a postdoctoral fellow then research associate position at Harvard University from 2006-2009, and joined Shanghai Jiao Tong University in 2009.
His expertise lies in the areas of optoelectronics and nanotechnology. He has worked on semiconductor nano lasers for photonic integrated circuits, microfluidics integrated nano optical sensors for sensitive biomolecule detection, single molecule and single chemical event detection by enhanced Raman spectroscopy, and fiber-optic integrated biomolecule sensing and chemical trace detection.
Host: EE-Electrophysics
Location: Hughes Aircraft Electrical Engineering Center (EEB) - 132
Audiences: Everyone Is Invited
Contact: Marilyn Poplawski
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor. -
MRI of Bound and Pore Water Concentration in Cortical Bone
Wed, Jun 22, 2016 @ 10:30 AM - 11:30 AM
Ming Hsieh Department of Electrical and Computer Engineering
Conferences, Lectures, & Seminars
Speaker: Mary Katherine Mansard, Ph.D., Vanderbilt University
Talk Title: MRI of Bound and Pore Water Concentration in Cortical Bone
Series: Medical Imaging Seminar Series
Abstract: The current standard for diagnosing fracture risk comprises measurements of bone mineral density (BMD), primarily by dual-energy X-ray absorptiometry (DXA). However, bone strength is affected by many factors other than BMD, such as architecture, collagen content, and porosity. Nuclear magnetic resonance (NMR) measures of the water bound to the collagen matrix (bound water) and free water occupying pore space (pore water) have shown promise in further assessing fracture risk. The work presented here translates NMR based techniques into Magnetic Resonance Imaging (MRI) methods using an ultra-short echo time (UTE) acquisition; the Double Adiabatic Full Passage (DAFP) sequence for measuring pore water concentration and the Adiabatic Inversion Recovery (AIR) sequence to measure bound water concentration. These imaging methods can be used to obtain maps of bound and pore water content throughout the cortical bone volume. MRI methods were first validated against NMR methods and shown to have good repeatability in vivo, and then were compared to whole bone material properties and found to show significant correlations with strength and toughness. The AIR and DAFP methods, initially carried out with 3D data acquisition, were further improved by implementing half-pulse 2D UTE sequences which significantly reduced scan times to under a minute. The sequences are now being applied in populations of healthy and osteoporotic patients for longitudinal evaluation. In short, measures of bound and pore water concentration have the potential to give a new and more thorough evaluation of bone characteristics and health that is not obtainable with currently used methods.
Biography: Mary Kate Manhard received her B.S. degree in Electrical Engineering from Clemson University in 2010 and completed her Ph.D. at Vanderbilt in Biomedical Engineering under the direction of Dr. Mark Does in 2016. She is a member of the Vanderbilt University Institute of Imaging Science, and her research focuses on using Magnetic Resonance Imaging (MRI) to probe cortical bone characteristics as a potential predictor of fracture risk. She has implemented bone imaging protocols for a 3T Philips clinical scanner, and has verified that MRI bone measurements report on ex vivo material properties of bone. Recently, she has been applying her work to osteoporotic patients to assess response to treatment using bone MRI measurements.
Host: Professor Krishna Nayak
Location: Hughes Aircraft Electrical Engineering Center (EEB) - 132
Audiences: Everyone Is Invited
Contact: Talyia White
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor.
