个人简介

B.S., 1985, North Carolina State University Ph.D., 1988, New Mexico State University Army Young Investigator Award, 1992; Outstanding Honors College Professor in the Sciences, University of South Carolina, 1994; Imaging Solution of the Year Award, Advanced Imaging Magazine, 1999; President, Coblentz Society, 2011; Gerald S. Birth Award in Diffuse Reflection, 2012.

研究领域

Physical

Optical spectroscopy is a potent tool for investigating chemical and biological systems. However, many systems of interest are heterogeneous – they consist of particles, films or films on particles. Often they are not pure samples, but consist of mixtures of particles. These are challenging samples on which relatively little work has been done. A series of projects over the last several years have lead our group into a greater and greater appreciation for the optics of particles and films. The following sections describe three projects we are currently pursuing with federal funding in the area of particle and film spectroscopy. Phytoplankton Spectroscopy Characterization of phytoplankton community composition is critical to understanding the ecology and biogeochemistry of the oceans, including the ocean’s response to global climate change and health issues related to coastal eutrophication. Phytoplankton use photosynthesis to produce fixed carbon and are thus key players in pelagic food webs. Many phytoplankton species also form harmful algal blooms (HABs) and can release toxins into the environment that create health problems or kill fish, marine mammals and humans. The traditional method for identifying phytoplankton species is light microscopy. The invention of electron microscopy increased our resolution power considerably, but both of these approaches require extensive training of the operator in algal taxonomy, and preparation and examination of samples is tedious and time consuming. More automated, image-based identification techniques are under development, but generally are not as accurate as the human eye. Chemotaxonomic (HPLC-based) approaches, where biomarker photopigments are used along with matrix-based algorithms, are faster and require less taxonomic training to identify phytoplankton, but samples still need to be extracted before data are acquired. Fluorescence excitation spectra of individual cells of three species. The area-normalized fluorescence excitation spectra of 77 E. huxleyi (black), 46 T. pseudonana (yellow) and 76 Synechococcus sp. (pink) cells excited in 2 nm increments over the range of 350 to 650 nm with a spectral resolution of ~10 nm. The inset shows the same spectra renormalized in the wavelength range for best classification, 550 to 610 nm. Fluorescence spectroscopy, using excitation and/or emission spectra, provides a non-invasive, non-destructive alternative approach to pigment-based identification, and phytoplankton can be examined intact. With this approach, chlorophyll a (chl a; found in all phytoplankton) and accessory pigments (carotenoids and/or accessory chlorophylls depending on the algal taxa) are excited by a broad spectrum lamp and the resulting fluorescence of chl a is detected near 680 nm. The usual approach involves analyses of bulk water samples. These, however, may be confounded by interference from fluorescence of chromophoric dissolved organic matter (CDOM) or suspended (non-living) particulate matter in the surrounding medium. The research groups of Prof. Timothy Shaw and Prof. Tammi Richardson (Biological Sciences) have been working with us to address this problem. With NSF support, these three research groups have collaborated to develop a ship-board instrument based on the technique of multivariate optical computing. Schematic of fluorescence imaging photometer. Ex, the excitation source is a Sciencetech 500-200 75W Xe Arc lamp and K is a ~2.5mm aperture. The lenses, in order of excitation to emission, are as follows: L1 is a 1 in. diameter biconvex lens with a focal length of 1 in., L2and L3 are 2 in. diameter planoconvex lenses with 6 in. focal lengths, and L4 is a 2 in. diameter biconvex lens with a 4 in. focal length. The filters are as follows: F1 is a 550-610nm Chroma bandpass (HQ580/60), F2 is an OG 530 Schott long pass, F3 is an OG 590 Schott long pass and F4 is a 681±5 nm Omega Optical (HBP10) bandpass. BS is an Omega Optical 2 in. diameter dichroic beamsplitter (640drlp). The filter wheel, W, is a Thorlabs FW103, powered by a Faulhaber 2057B brushless motor. The objective, M, is a Nikon, Plan Fluor, 60x magnification, 0.70 NA objective. The sample is contained in a beaker, S, and is pulled the flow cell, C, by a Cole-Parmer 75211-10 gear pump, G, to a waste beaker, R. The fluorescence emitted by the sample is passed back through the objective, M, and beamsplitter, BS, and imaged onto a back-illuminated Princeton PIXIS 1024B CCD. Preprocessed data image. There are 2 tracks of the coccolithophore E. huxleyi visible in this image; however, only the track near column 64 is well modulated and therefore, considered “good.” A histogram of the ratios for 518 E. huxleyi streaks and 335 T. pseudonana streaks shows the species are perfectly separated by their ratios. Forensic Infrared Imaging We are working in collaboration with the Morgan research group to develop improved methods for visualizing biological fluids and residue at crime scenes. Fourier transform infrared spectroscopy (FTIR) is a promising detection method for biological materials because of the distinctive chemical nature of biological solids. We have recently demonstrated a thermal infrared reflectance approach to visualizing and using chemical contrast for the detection and determination of protein-like stains, published in a series of reports in the journal Analytical Chemistry. At present, we are developing prototype instruments for future, and improving on the hardware and software developed in our first demonstration project. Figure 7. Multimode thermal imaging. (bottom left) This image is a “conventional” thermal image of a fabric attached to a piece of plywood. The bright circular object on the right is a reflectance standard for comparison. A dark circle in the center of the fabric marks the position of a screw head beneath the fabric. (top left) This is the same scene as the bottom left, but analyzed with an AC technique that gives reflectance instead of emittance. A polymer film applied to the fabric in the shape of the USC logo is revealed. In addition, the grain of the wood is visible. (top right) The same scene as in the top left, but viewed through a cast film of the same polymer. The contrast of the polymer on the fabric has been reduced. (bottom right) A ratio image made with the two top images.

近期论文

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Joseph A. Swanstrom, Laura S. Bruckman, Megan R. Pearl, Michael N. Simcock, Kathleen A. Donaldson, Tammi L. Richardson, Timothy J. Shaw and M.L. Myrick. ""Taxonomic Classification of Phytoplankton with Multivariate Optical Computing, Part I: Design and Theoretical Performance of Multivariate Optical Elements."" Appl. Spectrosc. (2013), 220-9. Joseph A. Swanstrom, Laura S. Bruckman, Megan R. Pearl, Elizabeth Abernathy, Tammi L. Richardson, Timothy J. Shaw, and M. L. Myrick. ""Taxonomic Classification of Phytoplankton with Multivariate Optical Computing, Part II: Design and Experimental Protocol of a Shipboard Fluorescence Imaging Photometer."" Appl. Spectrosc. 67 (2013), 230-9. Megan R. Pearla, Joseph A. Swanstroma, Laura S. Bruckmana, Tammi L. Richardsonb, Timothy J. Shawa, Heidi M. Sosikc and M.L. Myricka*. ""Taxonomic Classification of Phytoplankton with Multivariate Optical Computing, Part III: Demonstration."" Appl. Spectrosc. (2013), 240-7. M.L. Myrick and Stephen L. Morgan. ""Infrared Specular Reflection Calculated for Polymer Films on Polymer Substrates: Models for the Spectra of Coated Plastics."" Spectroscopy 27, number s8 (supplement) (2012), 8-25. Nichola Townshend, Alison Nordon, David Littlejohn, Michael Myrick, John Andrews and Paul Dallin. ""Comparison of the determination of a low concentration active ingredient in pharmaceutical tablets by backscatter and transmission Raman spectrometry."" Anal. Chem. 84 (2012) 4671-4676. Laura S. Hill, Tammi L. Richardson, Joseph A. Swanstrom, Kathleen A. Donaldson, Michael Allora, Jr., Timothy J. Shaw and Michael L. Myrick. ""Linear Discriminant Analysis of Single-Cell Fluorescence Excitation Spectra of Five Phytoplankton Species."" Appl. Spectrosc. 66 (2012), 60-65. M.L. Myrick, Megan Baranowski, Heather Brooke, Stephen L. Morgan, Jessica McCutcheon. ""The Kubelka-Munk Formula Revisited."" Applied Spectroscopy Reviews 46 (2011), 140-165. Megan Baranowski, Heather Brooke, Jessica McCutcheon, Stephen L. Morgan, M. L. Myrick. ""Coating Effects on Mid-Infrared Reflection Spectra of Fabrics."" Applied Spectroscopy 65 (2011), 876-84. Heather Brooke, Megan R. Baranowski, Jessica N. McCutcheon, Stephen L. Morgan, and Michael L. Myrick. ""Multimode Imaging in the Thermal Infrared for Chemical Contrast Enhancement. Part 1: Methodology."" Anal. Chem. 82 (2010), 8412-20. Heather Brooke, Megan R. Baranowski, Jessica N. McCutcheon, Stephen L. Morgan, and Michael L. Myrick. ""Multimode Imaging in the Thermal Infrared for Chemical Contrast Enhancement. Part 2: Simulation Driven Design."" Anal. Chem. 82 (2010), 8421-26. Heather Brooke, Megan R. Baranowski, Jessica N. McCutcheon, Stephen L. Morgan, and Michael L. Myrick. ""Multimode Imaging in the Thermal Infrared for Chemical Contrast Enhancement. Part 3: Visualizing Blood on Fabrics."" Anal. Chem. 82 (2010), 8427-31. Laura S. Hill, Tammi L. Richardson, Luisa T.M. Profeta, Timothy J. Shaw, Christopher J. Hintz, Benjamin S. Twining, Evelyn Lawrenz, Michael L. Myrick. ""Construction, Figures of Merit and Testing of a Single-Cell Fluorescence Excitation Spectroscopy System."" Rev. Sci. Instrum. 81 (2010), article 013103 (13 pgs). M.L. Myrick, Luisa T.M. Profeta and Megan Baranowski. ""An Experiment in Physical Chemistry: Polymorphism and Phase Stability in Acetaminophen (Paracetamol)."" J. Chem. Ed. 87 (2010), 842-4.