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The Meyer Group

The Meyer Group

The Meyer Lab has a wide range of research interests based in transition metal chemistry. We have multiple ongoing collaborations with professors in both biological to physical chemistry.

The unifying theme of our many projects is energy conversion. By studying the basic principles of electron transfer, excited states, and redox catalysis, we hope to advance the frontier of knowledge in renewable energy research. For example, we are currently investigating mechanisms of proton-coupled electron transfer, in order to understand how water is oxidized by Photosystem II during photosynthesis.

 

The Dempsey Group

The Dempsey Group

The Dempsey Group studies charge transfer processes involved in solar energy capture and conversion including photo-induced electron transfer and redox catalysis. The group utilizes methods of physical inorganic chemistry, such as electrochemistry and transient absorption spectroscopy, to examine the pathways of charge transfer in various energy conversion systems. These studies are elucidating the mechanisms employed by coordination complexes to catalyze the reduction of protons to hydrogen fuel and identifying pathways by which sunlight can be utilized to directly drive multi-electron, multi-proton chemical transformations. The group is also investigating how electrons can be efficiently transferred across the semiconductor interface in order to understand how to integrate solar energy capture and fuel production.

 

Valerie Ashby to Duke

Valerie Ashby

We are extending our heartfelt congratulations to Professor and Chair Valerie Ashby, who has been appointed the new Dean of Arts and Sciences at Duke University. As she has unfailingly done here at Carolina, she will most assuredly bring her outstanding leadership and charisma to that school. We are of course disappointed to see her go but are grateful for all that she has done for us here at the Department of Chemistry, and we wish her well in her new endeavor.

 

Analysis of Sphingosine Kinase Activity

Sphingosine-1-phosphate, S1P, a lipid second messenger formed upon phosphorylation of sphingosine by sphingosine kinase ,SK, plays a crucial role in natural killer, NK, cell proliferation, migration, and cytotoxicity. Dysregulation of the S1P pathway has been linked to a number of immune system disorders and therapeutic manipulation of the pathway has been proposed as a method of disease intervention.

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However, peripheral blood NK cells consist of a highly diverse population with distinct phenotypes and functions and it is unknown whether the S1P pathway is similarly diverse across peripheral blood NK cells. In a collaborative work, published as a cover article in Integrative Biology, researchers in the Allbritton Group, measured the phosphorylation of sphingosine–fluorescein, SF, and subsequent metabolism of S1P fluorescein, S1PF, to form hexadecanoic acid fluorescein, HAF, in 111 single NK cells obtained from the peripheral blood of four healthy human subjects. Substantial heterogeneity in S1P production and metabolism across cells within and between subjects was readily apparent. NK-cell subpopulations may exist with respect to SK activity and individual humans may possess distinct phenotypes. A deeper understanding of lipid signaling at the single-cell level will be critical to understand NK cell biology and disease.

 

Goldwater Scholar

We are very proud to announce that Kaitlyn Tsai has been selected as a Barry Goldwater Scholar. The Barry Goldwater Scholarship Program was established by Congress in 1986 to honor Senator Barry Goldwater, who served his country for 56 years as a soldier and statesman, including 30 years of service in the U.S. Senate. The purpose of the Foundation is to provide a continuing source of highly qualified scientists, mathematicians, and engineers by awarding scholarships to college students who intend to pursue research careers in these fields.

Kaitlyn Tsai

Kaitlyn Tsai is from Apex, North Carolina where she went to Apex High School. She feels that she came to the Department of Chemistry at Carolina, almost by accident since she came in with a lot of AP credit. Later, she has come to believe that choosing chemistry was one of the best decisions she could have made for her undergraduate studies. She claims that "between the amazing faculty and extensive opportunities for research," she has "become more inspired to pursue chemistry research." Her initial choice was to start as Chemistry B.S. major, but after taking genetics, she became more interested in the biological applications of chemistry and switched to the biochemistry track. Kaitlyn is currently conducting research in Dr. Marcey Waters' Bioorganic Chemistry lab, where she is part of a team investigating protein binding involved in histone methylation for epigenetic regulation. Dysregulation of histone methylation has been associated with certain types of cancers, and the eventual development of inhibitors molecules to correct for epigenetic malfunction is the end goal of this research. After graduation, Kaitlyn intends to enroll in a Ph.D. program in Chemistry, and hopes to continue epigenetic research. She would also like to stay in academia since it would give her the opportunity to teach and mentor. -Congratulations to the very prestigious award, Kaitlyn!

 

Copper in Water Oxidation

Copper metal is in theory a viable oxidative electrocatalyst based on surface oxidation to CuIII and/or CuIV, but its use in water oxidation has been impeded by anodic corrosion. Researchers from the Meyer Group, published in Angewandte Chemie, present the in situ formation of an efficient interfacial oxygen-evolving Cu catalyst from CuII in concentrated carbonate solutions.

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The catalyst necessitates use of dissolved CuII and accesses the higher oxidation states prior to decompostion to form an active surface film, which is limited by solution conditions. This observation and restriction led to the exploration of ways to use surface-protected Cu metal as a robust electrocatalyst for water oxidation. Formation of a compact film of CuO on Cu surface prevents anodic corrosion and results in sustained catalytic water oxidation. The Cu/CuO surface stabilization was also applied to Cu nanowire films, which are transparent and flexible electrocatalysts for water oxidation and are an attractive alternative to ITO-supported catalysts for photoelectrochemical applications.

 

Aerosol Analysis

Low-temperature plasma ionization, a technique that causes minimal fragmentation during ionization, has been investigated by the Glish Group as an ionization technique for mass spectrometric detection of the compounds in ambient organic aerosols in real time.

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The experiments presented in a paper published in Analytical Chemistry demonstrate that ions are generated from compounds in the aerosol particles. The utility of this technique for detection of both positive and negative ions from the pyrolysate of multiple natural polymers is presented. Ultimately, low-temperature plasma ionization is shown to be a promising ionization technique for detection of compounds in organic aerosols by mass spectrometry.

 

Hopping Diffusion of Nanoparticles

In a collaborative work, published in Macromolecules, researchers in the Rubinstein Group propose a hopping mechanism for diffusion of large nonsticky nanoparticles subjected to topological constraints in both unentangled and entangled polymer solids, networks and gels, and entangled polymer liquids, melts and solutions. Probe particles with size larger than the mesh size ax of unentangled polymer networks or tube diameter ae of entangled polymer liquids are trapped by the network or entanglement cells. At long time scales, however, these particles can diffuse by overcoming free energy barrier between neighboring confinement cells.

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The terminal particle diffusion coefficient dominated by this hopping diffusion is appreciable for particles with size moderately larger than the network mesh size ax or tube diameter ae. Much larger particles in polymer solids will be permanently trapped by local network cells, whereas they can still move in polymer liquids by waiting for entanglement cells to rearrange on the relaxation time scales of these liquids. Hopping diffusion in entangled polymer liquids and networks has a weaker dependence on particle size than that in unentangled networks as entanglements can slide along chains under polymer deformation. The proposed novel hopping model enables understanding the motion of large nanoparticles in polymeric nanocomposites and the transport of nano drug carriers in complex biological gels such as mucus.

 

 

At the Department of Chemistry, we feel strongly that diversity is crucial to our pursuit of academic excellence, and we are deeply committed to creating a diverse and inclusive community. We support UNC's policy, which states that "the University of North Carolina at Chapel Hill is committed to equality of opportunity and pledges that it will not practice or permit discrimination in employment on the basis of race, color, gender, national origin, age, religion, creed, disability, veteran's status, sexual orientation, gender identity or gender expression."