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Brent Casper will be presenting a seminar titled Development of an Extraction Method for the Analysis of Organic Gunshot Residue from Clothing.

Faculty Host: Dr. Bert Lynn

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Dr. Lisa McElwee-White of the University of Florida will be presenting a seminar titled Mechanism-Based Design of Precursors for the Deposition of Inorganic Films and Nanoparticles.

Abstract: Nanostructures can be deposited from organometallic and inorganic precursors by a variety of techniques including chemical vapor deposition (CVD), surface plasmon mediated chemical solution deposition (SPMCSD) and electron beam induced deposition (EBID).  A mechanism-based approach to designing precursors for these deposition methods requires consideration of the properties of the precursor compound and its probable decomposition pathways under the specific reaction conditions.  Examples will be chosen from CVD of metal nitride films, CVD of metal oxide nanorods, SPMCSD of gold nanoparticles on nanostructured Ag substrates and EBID of high metal content deposits.

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Quanzhen Huang of the University of Kentucky will be presenting a seminar titled Thermal Degradation of Amines for CO₂ Capture. 

Refreshments will be provided at this event.

Faculty Advisor:  Dr. John Selegue

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This event has been cancelled.

Dr. Geoffrey Coates of Cornell University will be presenting this year's Dawson Lecture, titled New Polymers from Old Monomers: Advances Enabled through Catalyst Design and Discovery.

Abstract: Although the chemical, physical, and mechanical properties of a polymer are the most vital factors in determining utility, another important constraint that must be considered is the cost of the material. The best way to create inexpensive new polymers is to start with large-scale commodity monomers, rather than rely on the development of new-to-the-world monomers. The focus of our work is the development of new synthetic methods for polymer synthesis, where known organic feedstocks are combined in alternative ways to make new macromolecular materials. We accomplish this through the development of metal-based catalysts that exhibit unique reactivity. In this presentation, the discovery, development and application of new catalysts for polymerization will be presented. The development of new methods for the synthesis of sustainable polymers will also be discussed. 

Refreshments will be served before the event in CP-114A/B.

Faculty Host: Dr. Susan Odom

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Dr. Tae-Hee Lee of Penn State University will be presenting a seminar titled Single Molecule Studies of Nucleosome Structure and Dynamics.

Abstract: The nucleosome is the fundamental packing unit of the eukaryotic genome. The structure and structural dynamics of the nucleosome are at the core of the mechanisms of gene regulation and maintenance. We studied the structure, structural dynamics, and assembly of nucleosome core particles and how these properties are altered by various epigenetic modifications based on single molecule fluorescence measurements. Our study revealed that these modifications induce changes in the nucleosome core particles that may directly or indirectly contribute to gene regulation activities. Our study demonstrates how single molecule methods can fill the niche not covered by the conventional structural biology tools.

Refreshments will be served at this event.

Faculty Host:  Dr. Chris Richards

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Bidhya Maharjan of the University of Kentucky will be presenting a seminar titled Ferrocene-Fused Derivatives of Polyacenes, Tropones and Thiepin.

Faculty Advisor: Dr. John Selegue

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Dr. Rajeev Misra of Arizona State University will be presenting a seminar titled In vivo Investigation of Bacterial Multidrug Efflux Pumps. 

Abstract: Multidrug resistance among human bacterial pathogens remains a grave social concern. A common cellular mechanism bacteria frequently employ is the efflux of antibiotics from the cell; resistance develops when the rate of drug efflux across the membrane exceeds that of drug influx. One of the most extensively studied multidrug efflux systems of the Resistance-Nodulation-Division (RND) family comprises of the AcrA, AcrB and TolC proteins of Escherichia coli. Fine structural analyses have provided deeper understanding of how drugs are captured and pushed through the AcrB pump protein. However, much remains to be learned as to how the tripartite pump assembles to extrude drugs from AcrB to outside the cell. I will discuss our efforts to gain a better understanding of the AcrAB-TolC pump assembly in vivo.

Due to their high clinical relevance, inhibitors have been sought to reduce or abolish the activity of multidrug resistant efflux pumps. Phenylalanine arginine β-naphthylamide (PAβN) was one of the first lead compounds that showed a potent inhibitory activity against a number of RND pumps, including AcrB. However, the conclusion that PAβN acts principally as an efflux pump inhibitor was questioned by several recent publications. We have attempted to resolve this controversy by employing strains constitutively expressing AcrAB or a homologous AcrEF efflux pumps. The employment of a modified real-time efflux assay allowed for the first time a clear distinction between the efflux pump-inhibiting activity of PAβN and membrane-permeabilizing action of polymyxin B nonapeptide (PMBN). It was determined that at low concentrations, PAβN acts mainly as an inhibitor of the AcrAB and AcrEF efflux pumps. However, at high concentrations, PAβN in the efflux-proficient background not only inhibited the efflux pump activity but also destabilized the membrane. The effects of PAβN on membrane integrity are compounded in cells unable to extrude PAβN.

Refreshments will be served at this event.

Faculty Host: Dr. Yinan Wei