Current Students and their Research
“Pretreatment Methods of Biomass for Ethanol Production and Microbial Conversion of Biomass to Ethanol”
With the recent IPCC report suggesting that the major cause of global warming is the burning of fossil fuels (IPCC 4th assessment report, 2007), the need to switch to cleaner, alternative energy sources is necessary and urgent. In order to meet the renewable energy goals set by various countries of the world there is need to devise practical, economical means to convert the inexhaustible energy source called lignocellulose biomass to glucose and thereafter to ethanol or other biofuels. The main problem in the conversion of lignocellulose biomass to ethanol is the difficulties in releasing cellulose from the complex entanglement of lignin and hemicellulose, enhancing enzyme accessibility to cellulose. We are examining existing pretreatment methods with the aim of developing a more-efficient pretreatment protocol. The ultimate goal is to produce ethanol at a competitive price as an alternative energy source. This research also includes the investigation of novel technologies that can potentially separate the product (ethanol) from other reaction bi-products. Lastly, we will investigate multiple microbial systems with the aim of overcoming some of the inhibitory effects associated with enzymatic bioconversion of biomass to biofuels.
“The Natural History, Survival, and Conservation Plan for the Timber Rattlesnake (Crotalus horridus) at Center Hill Lake in Tennessee”
The timber rattlesnake is facing serious threats throughout the United States. Originally found in 30 states, it has been extirpated from Delaware, Maine, and Rhode Island. It is protected from harvest in Tennessee and is listed as in need of management. Much of the distribution data in Tennessee is antiquated, and the current status of the species is in question (Wyatt and Bryan 2000). No studies of the natural history, distribution, demographics, or population size of timber rattlesnakes have been completed in Tennessee (Wyatt and Bryan 2000). Findings from this study can enhance Timber rattlesnake populations, which are clearly declining throughout its range. As development continues to expand, especially in somewhat remote, scenic areas such as Center Hill Reservoir, populations of wildlife will be displaced or extirpated from these areas. This study will identify and provide insight into necessary factors to develop conservation plans for Tennessee and other locations.
“Metal Extraction from Aqueous Solutions Using Thiosemicarbazone and Semicarbazone Chelating Resins”
The presence of heavy metals in natural waters is an increasing problem due to industry practices and man-made disasters, such as the ash spill at the TVA power plant in Harriman, TN. As the environmental consciousness of the population is raised, the demand for stricter regulations on the amounts of metals present in water sources will increase. This study presents the results of removing metal ions from aqueous solutions using a series of chelating resins. Dry weight distribution, Dw, values were measured by a batch technique for a series of resins containing different functional moieties at selected pH values. The results for the uptake of radioactive tracer metals as a function of pH, resin loading, and structure of the chelating group will be presented. These materials offer the potential to effectively extract and separate metals at environmentally important aqueous conditions.
“Development of Monitoring Protocols for Two Rare Fishes in Tennessee”
The National Park Service has proposed creation of monitoring programs for the duskytail darter Etheostoma percnurum in the Big South Fork National River and Recreation Area (BSF) and the spotfin chub Erimonax monachus in the Emory River watershed in response to declines in rare fish populations. The duskytail darter and spotfin chub are acceptable for monitoring because they are rare, endangered, and susceptible to environmental changes and disturbances. The goal of this research is to develop long-term monitoring protocols for the duskytail darter and spotfin chub. Specific objectives include: (1) develop and test specific sampling designs that provide the statistical power to detect changes in population size and contribute to increased precision in estimates, (2) develop capture efficiency models for underwater observation sampling methods for both species, (3) define critical habitat to aid in monitoring site selection, and (4) conduct a power analysis to assess the ability of protocols to monitor populations. The end result will be a set of fully developed, tested, and evaluated monitoring protocols that are available to the National Park Service and other entities focused on assessing rare fish populations.
“Establishing a Chemical Fingerprint Database of Clandestine Methamphetamine by LC/MS/MS and GC/MS/MS”
Over the years, illicit manufacture of methamphetamine has been a major cause of concern throughout the world. At every step of its presence, starting with the manufacturing, trafficking, consumption, or at the disposal, methamphetamine poses a serious health, social and environmental hazard. This research focuses on identifying and resolving some of the above issues. Firstly, the research focuses on determining the residential contamination caused by toxic chemicals liberated during the illicit manufacture of methamphetamine by off-site wipe testing and SPME-GC/MS/MS. The second research goal is to establish a chemical fingerprint database of seized clandestine methamphetamine by employing LC/MS/MS and GC/MS/MS. Finally, the research also aims to detect any trace amounts of methamphetamine that may be present in wastewaters by using LC/MS/MS and Q-TOF spectrometry.
Pyrolysis of biomass is the decomposition of organic material at high temperatures, usually between 200 – 400 °C. Fast pyrolysis occurs at heating rates that are unachievable in conventional thermal gravimetric instruments; still, slow pyrolysis kinetics using thermal gravimetric analysis (TGA) will be looked at in the early part of this research. The main focus, fast thermal degradation of biomass, must be approached by analyzing the gaseous pyrolysis products rather than by simply following the weight loss events. Furthermore, secondary gas-phase pyrolysis products will be taken into account as they play a significant role in the genesis of pyrolysis products. Rapid quenching will be used to quench pyrolysis while producing oily fractions with higher molecular weights. Mass spectrometry of gas-phase analytical methods will be explored to study biomass pyrolysis under realistic and industrially relevant conditions. Biomass kinetic parameters can be obtained and products can be analyzed and characterized. These two possibilities are of great interest in that kinetic parameters such as the reaction rate and the heat of reaction are essential in the design of a pyrolysis reactor. Also, by characterizing biomass pyrolysis product information, we can learn more about the components involved in this viable renewable energy source.
“Photochemical Redox Chemistry of Hg in Aquatic Systems”
Hg can exist in various stable oxidation states in the environment. Notable among them are Hg (0) and Hg (II). Elemental mercury vapor, Hg (0) has residence time of approximately 6 - 12 months in the atmosphere. Hg (II) is highly soluble in aqueous media and can be readily transported to the Earth’s surface from the atmosphere through atmospheric deposition (e.g. wet deposition such as rain or snow). Furthermore, it serves as a precursor for methyl mercury (HgCH3+), which eventually bioaccumulates in fishes and consequently becomes a risk for humans and wildlife alike. Therefore, the redox chemistry of mercury exerts significant impact on the distribution and transformation of Hg in various environmental compartments of the earth’s surface. Previous studies indicate that light can control Hg redox reactions. This research will be designed to study the effect of light on Hg oxidation and reduction in aquatic systems. The focus will be first on the reduction of Hg(II) to Hg(0). The effect of small molecular mass (LMM) organic acids and humic matter (humic acid, fulvic acid) on photochemical reduction of Hg(II) will be studied through lab simulation experiments. The ultimate aim of this research is to obtain the kinetics and reveal the mechanisms of photochemical redox of Hg in aquatic systems.
“Mathematical Modeling of Giant Canada Goose Social Biology in the Upper Cumberland Region of Tennessee”
Previous research of giant Canada geese in the Upper Cumberland (UC) region of Tennessee involved social biology, movement patterns, aggression and dominance, and nesting ecology. A comprehensive study of the social biology of the UC flock, including all past observational and capture data, will provide additional information on resident geese that should assist in management of migratory geese. The availability of over ten years of capture and observation data provides a rare opportunity to study productivity mechanisms and lifetime reproductive success for certain individuals. Long-term data also will facilitate analysis of observed social bonds. This study will attempt to discern the origin of social bonds, degree of relatedness of pseudofamily members, and mate selection/reproductive effort in terms of pseudofamily and subflock association.
"Degradation byPulse Corona Discharges: Study on the Possible Chemical Degradation Pathway for Diclofenac"
Industrialization has resulted in improving human living standards to a great extent. However, along with the improvements in living standards, pollution problems have also occurred. Our water supplies are a main issue of interest because pollution from both the atmosphere and soil eventually enters the aqueous phase by deposition and percolation respectively. Organic product contamination is one such problem.The removal of hazardous organic pollutants, such as, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (such as benzopyrene and dibenzoanthracene), pesticides (DDT, lindane), chlorinated aliphatic (chloroform, tetrachloromethane, trichloroethylene), pharmaceutical products (diclofenac, ibuprofen, carbamazepine), pollutants from mining, oil, and other related industries from waste water is a growing issue in environmental science and technology.Innovative methods for water remediation have been examined for removing contaminants from waste sites. Pulsed corona discharge (PCD) is a non-thermal plasma technology characterized by low gas temperatures and high electron temperatures. This technology has the potential of effective water decontamination and the capability of efficient removal or degradation of organic contaminants. Two key aspects (chemical and physical) exist during a pulsed corona discharge process, and are thought to occur simultaneously in synergism for direct or indirect degradation of organic compounds. The chemical aspect of the process, which is the main focus of this research, mainly involves the formation of various active radicals, such as, .OH. .H, .O, .O2 and .HO2 and active molecules, such as, H2O2 and O3 and their chemical reactions and pathways. All these active species and reactions involve a high oxidation potential to break the molecular bonds of organic contaminants; and, therefore, to lead to effective decontamination of water fluent.The group in Tennessee Technological University is focused on advancing the PCD technique for molecules larger than those being studied in the literature such as Phenol, Atrazine, Chlorophenol, etc. A combination of pH, conductivity, and physical aspects of the corona-generating system such as input power, frequency, and electrode distance, has been used to have physical aspects of the PCD.Using the fundamentals of organic chemistry with pulsed corona discharge principles, this research explores the degradation pathway of one of pharmaceutical products (diclofenac) in PCD using Q-TOF-MS and LC-MS-MS to identify the intermediate degradation products.
“Development of techniques to determine the bioavailability of organic pollutants in aqueous environments”
My research involves development of techniques to measure bioavailability of organic pollutants in aquatic environments. Our major approach is based on utilization of proteomic tools to identify differentially expressed proteins in aquatic organisms due to the presence of pollutants in the growth medium. Identification of differentially expressed proteins may be a direct indication of the bioavailability of the pollutants, may facilitate the development of new biosensors to detect bioavailability, and additionally may reveal the concealed impacts of the pollutants on the physiological processes of the organisms. We use microalgae Chlamydomonas reinhardtii as a model organism, and study the differences in its protein expressions as a response to triclosan, a commonly used antimicrobial compound found in many surface waters in trace amounts, present in the growth medium. The research plan involves growth of the alga in the presence and absence of triclosan in the medium, extraction and purification of proteins, 2-D electrophoresis, and mass spectrometric analysis of differently expressed protien.
Keith Gibbs "Effects of Antimycin Application for Native Brook Trout Restoration to Benthic Macroinvertebrate Communities in Lynn Camp Prong Watershed, Great Smoky Mountains National Park"
Antimycin, an aquatic pesticide, was applied to 12.8 km of Lynn Camp Prong and its tributaries in the Great Smoky Mountains National Park (GRSM) during September 2008 to remove non-native rainbow trout Onchorhynchus mykiss and restore a viable population of the native "Southern Appalachian" brook trout Salvelinus fontinalis. Chemical applications have become highly utilized fish removal and restoration tools and although antimycin is designed to minimize impacts to non-target species, benthic macroinvertebrate assessments are recommended, pre-and post-treatment, by National Park Service protocols (Moore 2008) to determine short- and long-term effects of antimycin application to aquatic macroinvertebrate communities.
Brianna Zuber "Distribution and abundance of the rare Barrens darter, Etheostoma forbesi"
The Barrens Plateau region of middle Tennessee harbors a number of unique and endemic aquatic species, including the Barrens darter (Etheostoma forbesi). The Tennessee Wildlife Resources Agency lists the Barrens darter as endangered; however, the Cookeville Field Office of U.S. Fish and Wildlife Service assessed the status of the Barrens darter during 2006 and chose not to recommend this fish be elevated to candidate status for Federal listing. This decision was based on the fact that this species has persisted, albeit in low numbers, across a number of sites during the period 1994 through 2004, with no apparent positive or negative trend in its status (Geoff Call, U.S. Fish and Wildlife Service, personal communication). However, surveys undertaken in 1994 (Madison 1995) and 2004 (Hansen et al. 2006) do not provide spatially explicit data concerning threats to Barrens darters, nor did the latter include an extensive sample of suitable habitat. Hansen et al. (2006) speculated that many suitable sites are situated upstream from previously sampled locales, and these sites should be visited to determine Barrens darter occupancy and better describe the extent of its distribution and abundance. The goal of the current research was to document the current distribution and abundance of the Barrens darter at most known historical collection localities and at additional localities within their potential range on the Barrens plateau.