Skip to content

Featured Research

October 2017- Mallory Ladd

Environmental and Climate Sciences

 

This month’s featured researcher is Mallory Ladd, who presented her work at the American Society for Mass Spectrometry’s 65th Annual Conference on Mass Spectrometry and Allied Topics held in Indianapolis, IN this past summer, and has been invited to give a talk on her dissertation project next month at the Southeast Regional Meeting of the American Chemical Society in Charlotte, NC.

 

Paper Title: Digging Deeper – Development and evaluation of a nontargeted metabolomics approach to identify biogeochemical hotspots in Arctic soils

Abstract: “Arctic soils contain twice as much carbon as what exists in the atmosphere and are warming twice as a fast as any other landscape on the planet. Rising temperatures are increasing permafrost thaw, both in depth and duration, threatening to increase microbial decomposition of soil organic matter and the release of CO2 and CH4 to the atmosphere. Reliably modeling where and when this release will occur requires knowledge of the chemical composition of soil organic matter; in particular, the most vulnerable or bioavailable fraction—low molecular weight (LMW) dissolved organic matter (DOM). Our understanding is limited, however, by the wide-ranging physicochemical properties and high fluxes of these compounds, posing significant challenges in detection, isolation, and quantification. The objective of this work was to establish a robust workflow, from sample collection to analyte annotation, to characterize LMW DOM with soil depth and from beneath two vegetation types that dominate the Arctic landscape. To achieve this, we evaluated a multi-dimensional separation using both reversed-phase (RP) and hydrophilic interaction (HILIC) liquid chromatography (LC), coupled with nano-electrospray (nanoESI), high-resolution tandem mass spectrometry (HRMS/MS) in positive and negative ion modes. Features were clustered based on accurate mass and fragmentation pattern, resulting in a matrix of thousands of peaks per sample. Peak areas for features not observed in the blanks or controls were compared across all samples, statistically significant differences with depth or between vegetation cover were determined, and the resulting list of features was matched to online databases. Annotated classes of LMW DOM compounds included plant and microbial metabolites, organic acids, osmolytes, sugars, simple peptides, and heterocyclic compounds. Based on the chemical profile, we were able to distinguish between samples at each depth and between vegetation types, suggesting that a molecularly-resolved, data-driven approach could enable more reliable predictions of how biogeochemical processes occurring at the molecular-scale (e.g. plant-microbial competition for organic nutrients) impact carbon fluxes in the Arctic at the landscape-scale.”


Previous research highlights from Bredesen Center graduate students.

Nannan Jiang

This month’s Bredesen Center Featured researcher is Nannan Jiang, who recently presented his work at the 16th International Symposium on Microbial Ecology (ISME) held in Montreal, Quebec, Canada. His conference poster can be seen on the fourth floor of Greve Hall.

“Though my current work focuses on environmental microbiology, I am actually a molecular geneticist by training. This combination has allowed me to take a deeper dive into the genetic basis that may determine the fate of toxic pollutants in our environment. Specifically, the pollutants addressed in this study are chlorinated solvents, which are commonly found in groundwater systems. While all of these chlorinated solvents are toxic, some are particularly noteworthy as they have been shown to be human carcinogens. Some of these toxins are naturally occurring, while most of them are derived through anthropogenic means. Fortunately, or perhaps fortuitously, a fascinating group of microorganisms has adapted to surviving in these chlorinated solvents, even to the point of breaking them down as the microorganisms grow and divide. However, these bacteria cannot clean up our environment by themselves, because they actually require unique cofactors to carry out this degradation process.

In this study, we identified a fragment of DNA that encodes an enzyme to make these required cofactors. Interestingly, this gene is actually harbored in a different bacterial species, meaning that multiple members of the microbial community must come together to clean up these toxic wastes spilling into our ecosystem. Remarkably, this project demonstrates energy derived from biological systems in multiple facets. Some microorganisms can degrade these toxic chlorinated solvents and in doing so, use them for energy. Meanwhile, other bacteria use different sources of biological energy to produce cofactors, a biologically-derived, value-added product similar to vitamins and antibiotics, to support this process of cleaning up our environment.”

Christine Ajinjeru

This month’s featured research was presented by Christine Ajinjeru at two conferences:

Society for the Advancement of Material and Process Engineering – SAMPE SEATTLE 2017 

Paper title: The influence of rheology on melt processing conditions of carbon fiber reinforced polyetherimide for Big Area Additive Manufacturing

Abstract: “An approach was presented for determining the melt processing conditions of high temperature amorphous thermoplastics, specifically carbon fiber reinforced polyetherimide (PEI), for Big Area Additive Manufacturing (BAAM). PEI is a high performance thermoplastic that is attractive for various high temperature applications in the automotive and aircraft industry. For PEI to be processed successfully with BAAM, it must be stable over a range of temperatures and print conditions to ensure the final part possesses the desired strength and modulus. Under this approach, thermal properties are first analyzed to identify the lower and upper operating limits for the polymer and then extensive rheological characterization is carried out at selected temperatures within these bounds. This study investigates the effect of temperature, fiber loading, and processing environment on rheology in order to identify suitable process parameters for extruding carbon-fiber reinforced PEI on BAAM.”

IEEE Power and Energy Systems PowerAfrica 2017 Conference in Accra, Ghana

Paper title: Development of a modeling framework to forecast power demands in developing regions: Proof of concept using Uganda

 Abstract: “Accurate and detailed energy demand estimates are crucial to achieving adequate energy infrastructure planning. These estimates are often non-existent or deficient in many developing countries, and consequently, electricity supply is unreliable. A novel approach for estimating electricity demand is presented. Our approach uses a global geographical population database with 1km2 spatial resolution as the foundational input. The use of spatial population data is based on the premise that electricity consumption is dependent on where people are located. These population counts are converted to electrical customers to create spatial power demand data which can be mapped. The resulting power demand maps could be valuable for energy infrastructure planning. In this study, Uganda is used as a pilot case-study. Analysis suggests that an additional 1.5 GW of power generation capacity needs to be availed to meet the lowest power demand scenario. The methodology developed can be extended to other regions of interest.”

Christine’s poster can also be viewed on the fourth floor of Greve Hall.

Peter Shankles

This month’s featured research was presented by Peter Shankles at the Microfluidics, Physics & Chemistroy of Gordon Research Conference in Lucca (Barga), Italy.

Peter’s research poster can also be viewed on fourth floor of Greve Hall.

Abstract: “Additive manufacturing, or 3D printing, has been a cornerstone of the product development pipeline for decades, playing an essential role in the development of both functional and cosmetic prototypes. In recent years, the prospects for distributed and open source manufacturing have exploded, enabled by a growing library of materials, low-cost printers, and communities dedicated to platform development.

In this work, the production of multiple microfluidic architectures using a hybrid 3D printing-soft lithography approach is demonstrated and shown to enable rapid device fabrication with resolution high enough to take advantage of laminar flow characteristics. The fabrication process outlined here is underpinned by the implementation of custom design software that replaces computer aided design and slicer software. Devices are designed in the program by assembling parameterized microfluidic building blocks. The fabrication process and flow control within 3D printed devices were demonstrated with a gradient generator and two droplet generator designs, and 3D networks using bridge structures printed in a single motion rather than layers.”

Jessica Velez

This month’s featured research was presented by Jessica Velez at the 2017 Fungal Genetics Conference put on by the Genetics Society of America (GSA) in Pacific Grove, CA.

Her poster can be viewed on the fourth floor of Greve Hall.

Abstract: 

“Agriculture has become a multifaceted industry as the production of biofuels and the need for both greater productivity and sustainability grows in importance.  However, there is a finite amount of land available, and a portion of this land is unusable due to the presence of major pollutants, such as heavy metal contaminants. As the demand for agricultural land rises, the viability of crops within soils that were previously considered unusable has become more appealing.  There is a possibility that with modifications to the rhizosphere, a plant species may be able to survive in conditions that would otherwise be toxic to the plant, increasing overall land availability for use in agriculture.  This would allow the planting of biofuel crops within fields that may not be optimized for the growth of crops intended for consumption due to soil contamination, thereby avoiding the “food-for-fuel” tradeoff that has driven agronomic policy concerns in the corn-based ethanol industry.  Wild strains of Cenococcum geophilum are being isolated and characterized for genetic analysis.  These strains will then be screened with the heavy metals cadmium, lead, strontium, copper and zinc to determine susceptibility, and those strains demonstrating the greatest tolerance will be introduced to Populus in greenhouse experiments to determine the impact of fungal presence, if any, on the plant host.  This research will aim to lead to a greater understanding of the exchange that occurs within a plant-fungal system and determine if there is an increase in the overall hardiness of the plant when the fungal species are present and how this varies with the genetic makeup of the symbionts. Looking to the future, this research will impact the direction of biofuel crop production as knowledge of the plant-fungal relationship increases, as well as potentially open new land for agricultural development.”

Tony Wong

This month’s featured research was presented by Tony Wong at the Materials Research Society (MRS) Fall 2016 Meeting held in Boston, MA in November 2016 where his poster was awarded “Best Poster.”

Tony’s poster can be viewed in person on the fourth floor of Greve Hall.

This research is also published in APL Materials:

DOI: 10.1021/acssynbio.6b00189

Abstract: 

A. T. Wong, J. H. Noh, P. R. Pudasaini, B. Wolf, N. Balke, A. Herklotz, Y. Sharma, A. V. Haglund, S. Dai, D. Mandrus, P. D. Rack, and T. Z. Ward. “Impact of Gate Geometry on Ionic Liquid Gated Ionotronic Systems.” APL Materials 5 (2017)

“Ionic liquid electrolytes are gaining widespread application as a gate dielectric used to control ion transport in functional materials. This letter systematically examines the important influence that device geometry in standard “side gate” 3-terminal geometries plays in device performance of a well-known oxygen ion conductor. We show that the most influential component of device design is the ratio between the area of the gate electrode and the active channel, while the spacing between these components and their individual shapes have a negligible contribution. These findings provide much needed guidance in device design intended for ionotronic gating with ionic liquids.”

Humaira Taz

This month’s featured research was presented by Humaira Taz at the Materials Research Society (MRS) Fall 2016 Meeting held in Boston, MA in November 2016. Her oral presentation in symposium EM2:Rare-Earths in Advanced Photonics and Spintronics was one of the top three graduate student presentations, for which they were awarded graduate student prizes sponsored by Thorlabs and Elsevier. The talk was titled “Novel Room Temperature Ferromagnetic Semiconductor: amorphous Fe-Dy-Tb-Oxide”. This research is also published in Scientific Reports (doi: 10.1038/srep27869).

Our collaborator at University of Tennessee-Chattanooga, Dr. Tatiana Allen, and I also presented a poster at the same meeting. The poster focused on the changes in the conductivity, cation states, and magnetic properties of the Fe-Tb-Dy-Oxide as a result of annealing cycles. This poster was a finalist for the best poster award.

Humaira’s poster can be viewed here.

Abstract:

Humaira Taz, , Tamil Sakthivel, Nana K. Yamoah, Connor Carr, Dhananjay Kumar, Sudipta Seal & Ramki Kalyanaraman. “Ferromagnetism, optical transparency, and semiconducting behavior in Fe-Dy-Tb based amorphous oxide films”. Scientific Reports. 2017

“We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10−4 Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe0 oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics.”

Marie Kirkegaard

This month’s featured research was presented by Marie Kirkegaard at the National Technical Nuclear Forensics Center (NTNFC) Annual Academic-Laboratory Collaboration Meeting at Los Alamos National Laboratory (LANL) in August of 2016.

The ability to identify and characterize nuclear material in the wild is critical for nuclear security. While spectroscopic signatures have been cataloged for many of these materials, there has been less work done to understand how these signatures may be affected by environmental conditions.Marie’s current work examines uranyl fluoride, an important intermediate in the nuclear fuel cycle, using computational and spectroscopic methods to determine how the chemical and physical properties of the material change with environmentally-relevant perturbations in temperature and relative humidity.

Marie’s poster can be viewed in person on the fourth floor of Greve Hall or here. This research is also published in The Journal of Chemical Physics:

DOI: 10.1063/1.4973430

Abstract: 

M. C. Kirkegaard, J. Langford, J. Steill, B. Anderson, and A. Miskowiec. “Vibrational properties of anhydrous and partially hydrated uranyl fluoride.” The Journal of Chemical Physics (2017).

“Uranyl fluoride (UO2F2UO2F2) is a hygroscopic powder with two main structural phases: an anhydrous crystal and a partially hydrated crystal of the same R3¯mR3¯m symmetry. The formally closed-shell electron structure of anhydrous UO2F2UO2F2 is amenable to density functional theory calculations. We use density functional perturbation theory (DFPT) to calculate the vibrational frequencies of the anhydrous crystal structure and employ complementary inelastic neutron scattering and temperature-dependent Raman scattering to validate those frequencies. As a model closed-shell actinide, we investigated the effect of LDA, GGA, and non-local vdW functionals as well as the spherically averaged Hubbard +U correction on vibrational frequencies, electronic structure, and geometry of anhydrous UO2F2UO2F2. A particular choice of Ueff=5.5Ueff=5.5 eV yields the correct U–Oyl bond distance and vibrational frequencies for the characteristic Eg and A1g modes that are within the resolution of experiment. Inelastic neutron scattering and Raman scattering suggest a degree of water coupling to the lattice vibrations in the more experimentally accessible partially hydrated UO2F2UO2F2 system, with the symmetric stretching vibration shifted approximately 47 cm−1 lower in energy compared to the anhydrous structure. Evidence of water interaction with the uranyl ion is present from a two-peak decomposition of the uranyl stretching vibration in the Raman spectra and anion–hydrogen stretching vibrations in the inelastic neutron scattering spectra. A first-order dehydration phase transition temperature is definitively identified to be 125 °C using temperature-dependent Raman scattering.”

Patrick Caveney

caveney_patrick_2016a

This month’s featured research was presented by Patrick Caveney at the 2016 Synthetic Biology: Engineering, Evolution & Design (SEED) conference.

Patrick’s poster is available to view in the Bredesen Center offices on the fourth floor of Greve Hall or here. This research is also published in ACS Synthetic Biology:

DOI: 10.1021/acssynbio.6b00189

Abstract: 

Patrick M. Caveney, S. Elizabeth Norred, Charles W. Chin, Jonathan B. Boreyko, Brandon S. Razooky, Scott T. Retterer, C. Patrick Collier, Michael L. Simpson. “Resource sharing controls gene expression bursting.” ACS Synthetic Biology (2016).

“Genes express proteins in bursts of activity with periods of no activity between bursts. Burst dynamics are characterized by a burst size (duration of a burst) and burst frequency (number of bursts per time). During a burst the gene draws on a limited pool of reusable resource. Little is known about the relationship between burst dynamics and resource sharing. Here we made cell-sized reaction chambers (both PDMS plastic and POPC lipid vesicles) and observed bursting dynamics as the size of the resource pools was varied. When the size of the resource pool was increased, the number of protein made increased. This increase in protein was achieved by increasing the burst size not burst frequency. This may be due to the fact that the 100 different molecules needed to make protein became localized. Localized components suggest large transcriptional burst sizes are correlated with large translational burst sizes. This correlation is confirmed with in vivo E.coli data. Our results demonstrate the link between bursting dynamics and resource sharing.”

jhg

Patrick Caveney

caveney_patrick_2016a

 

This month’s featured research was presented by Patrick Caveney at the 2016 Synthetic Biology: Engineering, Evolution & Design (SEED) conference.

Patrick’s poster is available to view in the Bredesen Center offices on the fourth floor of Greve Hall or here. This research is also published in ACS Synthetic Biology:

DOI: 10.1021/acssynbio.6b00189

Abstract: 

Patrick M. Caveney, S. Elizabeth Norred, Charles W. Chin, Jonathan B. Boreyko, Brandon S. Razooky, Scott T. Retterer, C. Patrick Collier, Michael L. Simpson. “Resource sharing controls gene expression bursting.” ACS Synthetic Biology (2016).

“Genes express proteins in bursts of activity with periods of no activity between bursts. Burst dynamics are characterized by a burst size (duration of a burst) and burst frequency (number of bursts per time). During a burst the gene draws on a limited pool of reusable resource. Little is known about the relationship between burst dynamics and resource sharing. Here we made cell-sized reaction chambers (both PDMS plastic and POPC lipid vesicles) and observed bursting dynamics as the size of the resource pools was varied. When the size of the resource pool was increased, the number of protein made increased. This increase in protein was achieved by increasing the burst size not burst frequency. This may be due to the fact that the 100 different molecules needed to make protein became localized. Localized components suggest large transcriptional burst sizes are correlated with large translational burst sizes. This correlation is confirmed with in vivo E.coli data. Our results demonstrate the link between bursting dynamics and resource sharing.”

jhg

Akinola Oyedele 

oyedele_akinola_2016This month’s featured poster was presented by Akinola Oyedele at the Gordon Research Conference.

His poster is available to view below and in the Bredesen Center offices on the fourth floor of Greve Hall.

gordon-research-conference-poster_akinola_v02_kx

Riddhi Shah 

This month’s featured poster was presented by Riddhi Shah at the 5th International Symposium on Diffraction Structural Biology, where she was awarded 1st prize.

The poster is available to view in the Bredesen Center offices on the fourth floor of Greve Hall. .

 

 

 

[/collapse]

The flagship campus of the University of Tennessee System and partner in the Tennessee Transfer Pathway.