Spring 2009

Contact angle and dental practices

Dr. Chiayi Shen
Dept. of Dental Biomaterials
University of Florida

Hosting Dept: Physics, Astronomy and Geosciences–Engineering Studies Program

Conservation Agriculture: Past, Present, and Future

Paul M. White and Thomas L. Potter
Research Chemist USDA-ARS
Southeast Watershed Research Laboratory

Hosting Dept: Chemistry

Abstract:  Cultivation of crops 10,000 years ago led to settlements and ultimately civilizations in the Fertile Crescent region. Improvements in technology, namely the plow, allowed for more extensive farms and the surplus grain produced formed the first economies. However, over-exploiting the soil as a resource has also had detrimental impacts, including the fall of many civilizations. The industrial revolution resulted in the rapid expansion of farm equipment and the cultivation of the US Midwestern Great Plains. Persistent drought and extensive tillage led to the Dust Bowl of the 1930s. Current issues include sedimentation of the Louisiana coast and formation of a hypoxic dead zone in the Gulf of Mexico. Conservation tillage, encompassing cultivation technologies that reduce soil disturbance, can lead to dramatic improvements in soil and water conservation. Scientists at the USDA-Southeast Watershed Research Unit in Tifton, GA, study the hydrology and agrichemical transport in conventional tillage (Cvt) and conservation tillage (Cst) systems. Studies have demonstrated a two-fold decrease in surface runoff for Cst, as compared to Cvt, with a concomitant two-fold increase in lateral subsurface flow. While reducing sediment transport in Cvt, these changes can have important impacts on pesticide and nutrient fate. In addition to tillage, conservation measures such as cover cropping, companion cropping, and riparian buffer zones provide many benefits including increased biomass for ethanol production, soil carbon sequestration, and agrichemical interception. Future issues in conservation agriculture will focus on reduced water availability and a warming planet.

Modeling the Active Site of Nickel-Containing Superoxide Dismutase: A New Role for Nickel in Biology

Dr. Todd C. Harrop
Department of Chemistry
University of Georgia

Hosting Dept: Chemistry

Abstract:  The anionic superoxide radical is an inevitable product of aerobic respiration, which if not eliminated, may cause significant cell damage implicating this molecule in a variety of disorders. In order to combat such oxidative stress, all aerobic organisms possess metalloenzymes known as superoxide dismutases (SODs) that catalyze the disproportionation of superoxide to peroxide and molecular oxygen. Most recently, a new class of SODs has been discovered from Streptomyces soil bacteria and cyanobacteria that contain nickel at the active site. In contrast to other known SODs, Ni-SOD contains a square-planar Ni(II) ion ligated in an N2S2 environment consisting of one deprotonated peptide-N, one primary amine-N from the N-terminal histidine residue, and two cysteine-S donors. Ni-SOD is also unlike any other Ni-protein present in biology. In order to gain a fundamental understanding of the properties and mechanism of catalysis of this unique metallocenter, our lab has developed synthetic routes towards molecular structures analogous to the active site of Ni-SOD. The synthesis, structure, and reactive properties of Ni complexes housed in a mixed N,S ligand environment with spatial disposition and electronic features similar to the active site of Ni-SOD will be presented.

Achieving Sustainability through Revolutions in End-Use Applications of Thermal Energy

Dr. Srinivas Garimella
Director of Sustainable Thermal Systems Laboratory
School of Mechanical Engineering at Georgia Tech

Geoarchaeology of Governor's Island in New York Bay

Dr. Donald Thieme
Valdosta State University

Hosting Dept: Physics, Astronomy and Geosciences

Abstract:  Governors Island is a prominent landmark in New York Bay which recently changed hands when the United States Coast Guard moved off of the island. Recently completed geological investigations provide new information about how the island formed and how people shaped the surface of the island over time. Historic deposits are found in several locations on the original, northerly portion of the island. Sediments which contain artifacts and other
cultural residues are rich in organic matter, available phosphorus, lead, and zinc. Basal sediments which have not been affected by human activity
show differences in grain size that suggest a variety of depositional environments. Radiocarbon dates suggest that the deposits examined span the
time from the end of the last ice age to the present. Shoreline deposits on the island contain marine shell and shell hash and occur well above the
elevation of the present shoreline.

A time scale model for interacting wild and transgenic mosquito population

Dr. Billy Jackson
Valdosta State University

Hosting Dept: Math & Computer Science

Abstract:  Biologists discovered the genetic code for the mosquito in 2002. This discovery has led to investigating the possibility of altering or removing specific genes in order to hinder the population’s ability to transmit diseases to humans. The question of effectiveness of such a strategy has been posed to the mathematics community. In particular, we want to know if it is possible to introduce genetically altered mosquitoes into a wild population and have the emerging heterogeneous offspring (which would be unable to transmit the diseases as well) dominate in the population. Such questions deal with population dynamics, and there have been several recent papers by some mathematicians dealing with this issue. However, the models have been based on continuous and discrete domains. Mosquito populations are notorious for their duality in nature: they tend to exhibit continuous growth at times and discrete growth at other times. Thus, I will propose a model which is hybrid in nature to examine the dynamics using a new area of mathematics called time scales analysis.

TBA

Jason G. Romine, Ph.D.
Florida Program for Shark Research Florida Museum of Natural History
University of Florida
Gainesville, FL

Hosting Dept: Biology

Spring Break Week

Reading Chemical "Fine Print": The Key to Exploiting Nature's Isotopic Complexity

Dr. Alan Marshall Robert O. Lawton Professor of Chemistry & Biochemistry

Director, Ion Cyclotron Resonance Program National High Magnetic Field Laboratory

Florida State University

Hosting Dept: Chemistry

Abstract:  Most mass analysis relies on "nominal" mass accuracy (i.e., to within 1 Da). However, more and more applications are based on much more accurate mass measurement. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) offers 10-100 times higher mass resolving power than other mass analyzers. High mass resolving power (m/?m50% > 400,000 over a wide mass range) offers two major advantages. First, it becomes possible to separate complex mixtures without prior chromatographic or gel separation. Second, elemental composition may be determined from accurate (to <1 ppm) mass measurement alone for unknown molecules up to ~1,000 Da. Examples from environmental, petrochemical, analytical, and biological (especially proteomics) problems will be presented, including world records for mass resolution.

Are There Spuriously Induced Temperature and Precipitation Trends in the Southeast United States?

Dr. Jason Allard
VSU Department of Physics, Astronomy, and Geosciences

Hosting Dept: Physics, Astronomy, and Geosciences

Abstract:  The National Climatic Data Center (NCDC) has subdivided the contiguous United States into 344 climate divisions – areas representing nearly homogeneous climate regions.  Forty-five of these climate divisions comprise the six state region of the Southeast U.S.  While these data have been used in a variety of capacities, some argue that these data should be used judiciously, particularly with decadal- to century-scale climate change studies.  The problem is that long-term trends in these data may be spuriously generated by the methods used to calculate the divisional datasets.  These methods involve using all data available at a given time within a division, despite changes in the total number of stations and their locations through time.  This study documents differences in annual temperature and precipitation trends between the NCDC Climate Division database and the United States Historical Climate Network (USHCN) for the Southeast United States.  Correlation and multiple regression techniques indicate that the migration of the mean latitude, longitude, and elevation of NCDC stations within climate divisions impact the magnitude and the direction (i.e., increasing or decreasing) of the trends present in the divisional climate data relative to the USHCN dataset.  These results are statistically significant, and explain some of the variances between the temperature and precipitation trends of the two datasets.

Fault slip rates and the distribution of strain along an evolving segment of the Pacific-North America plate boundary

Dr. Kurt Frankel
Georgia Institute of Technology

Hosting Dept: Physics, Astronomy, and Geosciences

TBA

Travis Key
Biology Graduate Student
Valdosta State University

Hosting Dept: Biology

Imaging dynamic events inside living cells

Dr. Christine K. Payne
School of Chemistry and Biochemistry
Georgia Institute of Technology

Hosting Dept: Chemistry

Abstract:  Cellular health depends on a countless number of chemical reactions. Recent developments in microscopy, cell biology, materials science, and molecular biology have created a unique opportunity to directly observe chemical reactions as they occur within a living cell. It is now possible to label specific biomolecules with bright fluorescent probes made from naturally fluorescent proteins, synthesized organic molecules, semiconductors, or noble metals. These labeled biomolecules can be excited by lasers with a range of wavelengths and imaged with ultrasensitive cameras and photodiodes. These methods make it possible to understand the chemical reactions essential to biological function by imaging specific proteins or biomolecules directly as they undergo their normal functions within a single cell. Research in the Payne Lab is focused on both understanding intracellular chemical reactions and developing new methods for imaging dynamic events within cells. This seminar will discuss two types of chemical reactions; the enzymatic degradation of lipids and the aggregation of proteins involved in Huntington’s disease, as well as the imaging technology necessary to observe these events within living cells.

Last week of classes