Richard Ambler
College: Lyon College
Rowlen Group
Project Title: Identification of Whole Cells with Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry and Protein Database Inquires
Project Abstract: Matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry was used to analyze whole cells. Two strains of Escherichia coli were used as models for evaluation of sample treatment methodologies. Mass spectral peaks were identified for one E. coli (ATCC No. 23724), and protein searches in the Swiss-Prot/TrEMBL database were conducted in order to attempt identification of the sample as E. coli. Two types of cancerous cells, K562 and Jurkat, were also analyzed in the MALDI using the same basic methodology that was used to sample the two strains of E. coli. Mass spectra with identifiable peaks were observed for these cells. This work represents a preliminary step toward the possibility of differentiating between cancerous and non-cancerous cells.
Nicholas Betts
College: Wartburg College
Lineberger Group
Project Abstract: While the photoelectron spectrometer (PES) at CU/ JILA has been in existence for nearly 30 years and calibration of the laser tube has taken place at many times, there seem to be only vague notes on how exactly to produce the W- anion required in order to carry out the electron energy scale calibration for the replacement of the laser tube (6) . In the past finding W- has been an arduous task. It would often take a few weeks to find the ion with the previously used method. With the current calibration this summer using tungsten it was much the same case as before, but instead five weeks were spent in vain trying to find W- by the old technique. Eventually, though, the group developed a slightly different technique, which hopefully will take much of the guesswork out of finding W-.
Cheryl Billstrom
College:
University of San Diego
Jonas Group
Project Title: Polar Solvation Dynamics of Solvatochromic Dyes
Project Abstract: From both experimental and literature research, three common solvatochromic dyes have shown that the polar contribution to the bandwidths of absorbance and emission are different. This information found from IR144, Coumarin 153, and Betaine 30 is useful in describing the solvation dynamics of polar molecules in polar solvents. It is likely that there are other solvatochromic dyes like these three, and increases the possibility to predict the solvation dynamics of polar dyes in polar solvents in greater detail in the future.
Andrew Crowther
College:
Washington University in St. Louis
Nesbitt Group
Project Title: Using Distributed Gaussian Basis Sets to Model Two Dimensional Vibrational Systems
Project Abstract: Distributed gaussian basis sets
(DGB) are used to determine the vibrational
eigenvalues and eigenfunctions of various one and two
dimensional potential energy surfaces. This information is then used to
determine the Frank-Condon Factor from a bound electronic ground state
to a
dissociative excited electronic excited state. The most
favorable transition energy is determined by "discretizing" the electronic
excited potential and determining the absorption cross section from a state
in the electronic ground state to all the "discrete"
vibrational states in the electronic excited states. Using a distributed
gaussian basis set allows these calculations to be done quickly, and with
exceptional
accuracy.
Erika Hewitt
College: Loras College
Tolbert Group
Project Title: Formation and Characterization of Internally Mixed Ammonium Sulfate/Maleic Acid Aerosols
Project Abstract: Organic compounds represent a major fraction of the total aerosol, but little is known regarding their compositional characteristics, properties, or role in atmospheric chemistry. Recent studies have shown evidence that large amounts of organics are combined in the same aerosol particles as the sulfates. This experiment focused on the formation and qualitative characterization of the mixed ammonium sulfate/maleic acid aerosols using the scanning electron microscope. Pure ammonium sulfate and maleic acid submicron aerosols, as well as mixed ammonium sulfate/maleic acid aerosols, were created through the use of a constant output atomizer (TSI model 3076) fed by a Harvard Apparatus 22 syringe pump. The resulting electron microscope (SEM) images indicated that the mixed ammonium sulfate/maleic acid aerosol particles are internally mixed, and that when dried using a diffusion dryer and sulfuric acid bath they retain their mixed state and structure.
Paul Jang
College: UNC- Chapel Hill
Leone Group
Project Title: Mechanism for the formation of Dome-Shaped Ge Quantum Dots on Si(100)
Project Abstract: The deposition of Ge on Si (100) follows the Stranski-Krastanov growth mode. The deposition of germanium initially leads to formation of pyramid-shaped islands, which change in shape and increase in size to form domes. Different growth conditions were performed in molecular beam epitaxy experiments to decipher the mechanism of this transition. Images of the surfaces were taken using atomic force microscopy. The growth experiments performed suggest more than one mechanism is involved in the pyramid to dome transition. Intermixing occurs very slowly at the temperatures tested (775 K – 875 K); a long period of post-deposition annealing is required for intermixing to occur. Ostwald ripening of the domes also occurs during long annealing times. A rapid mechanism of island merging may possibly take place with high coverage or high flux. The density of pyramids on the surface and the deposition flux appear to be important factors in the ease of dome formation through merging. From the knowledge of the conditions required for the pyramid to dome transition, the formation of domes was suppressed in order to form a surface with a single size distribution of islands. Intermixing and Ostwald ripening were prevented with a short post-deposition annealing time. Merging was prevented with low island coverage and deposition flux. A surface with a high density of pyramids was achieved.
Nicholas Lowe
Project Title: A Novel Method of Protein Complex Identification in Mammalian Cells
Project Abstract: A two step purification procedure has been developed for the purification of Eukaryotic intracellular proteins expressed at their natural level under native conditions. The procedure uses a tandem affinity purification (TAP) tag consisting of a two IgG-binding units of protein A of Staphylococcus aureus (ProtA) followed by two TEV cleavage sites, the calmodulin-binding peptide (CBP), and the FLAG tag upstream of the protein of interest. The advantage of this method is high protein purity and the identfication of interacting proteins for the characterization of cellular pathways. The binding proteins are relatively small, allowing the protein of interest to be near its native form and maintain function. FLAG vs. CBP second step purification methods and reaction parameters were analyzed to optimize protein purity and yield of the Smad3 protein.
Kimberly O'Malley
Project Title: Glucosamine Potentially Reduces Inhibitory Effects of 3'-Azidothymidine (Zidovudine) on Protein Glycosylation
Project Abstract: In this paper we report that glucosamine is potentially effective in lessening the negative effects of AZTMP (3’-azido-3’-deoxythymidine monophosphate), the primary intracellular metabolite of AZT, on glycosylation reactions in whole cells. Previous studies in our laboratory have show AZTMP to be an extremely potent competitive inhibitor of pyrimidine nucleotide-sugar import into the Golgi lumen (2). The absence of the proper nucleotide-sugars within the Golgi complex results in several undesirable effects, including inhibition of lipid and protein glycosylation as well as dramatic changes in the biosynthesis of N-linked oligosaccharides (4). Our results suggest that the addition of glucosamine to K562 cells treated with AZT creates an excess of cytosolic nucleotide-sugars, specifically UDP-acetylglucosamine, which are then available for competition with excess AZTMP for transport into the Golgi. The successful shielding of glycosylation reactions by glucosamine may suggest a novel way in which long-term side effects of AZT, such as anemia and neutropenia (thought to be caused by modifications in glycosylation of cell surface proteins), can be minimized.
Elizabeth Pleshe
Project Title: Size-Dependent Kinetics of Polystyrene Nanosphere Photobleaching
Project Abstract: Photobleaching of polystyrene nanospheres forms a significant experimental barrier to the use of these microspheres in instrument calibration and biological experimentation. Particularly during experiments, which require excitation through a laser source, the rapid rate of photobleaching often impedes the progression of the experiment. In this study a kinetic evaluation of the photobleaching rate among polystyrene nanospheres of 26 +/- 2nm, 44 +/- 5nm, and 100 +/- 5nm was performed with the intention of finding a decay coefficient. This study was performed through continuous time scans of fluorescence emission under 488nm excitation. Results indicate that polystyrene nanospheres do indeed photobleach with time however a precise kinetic evaluation was not achieved due to experimental complications in monitoring light intensity.
Eric (Ryan) Smith
Project Title: Investigation of the Mechanism of Ammonia Catalysis in the Binary Reaction Producing SiO2 Deposition on Silica Particles
Project Abstract: A thin film of SiO2 can
be deposited one atomic layer at a time (by atomic layer deposition, or
ALD) by repetition of a binary reaction sequence:
A) SiOH* + TEOS ---> Si-O-Si(OEt)3* + HOEt
B) SiOEt* + H2O ---> SiOH* + HOEt,
where the asterisk (*) signifies the species located
on the surface. Ammonia gas acts as a catalysis for this reaction
because NH3 is thought to hydrogen bond with the surface silanols (geminal,
or isolated, hydroxyl groups), creating a lower energy intermediate state
which can increase the rate of reaction of the tetraethoxysilane (TEOS)
species in the A reaction. Infrared spectroscopy was used in a series
of experiments intended to determine the features associated with the adsorption
of NH3 on the SiO2 surface, H2O adsorption on the SiO2 surface, and NH3
adsorption on the TEOS-reacted SiO2 surface. Experiments were performed
under constant temperature with increasing gas pressure (isothermal conditions)
and constant pressure with increasing temperature (isobaric conditions).
The experiments measuring adsorption on the clean silica surface showed
an isolated hydroxyl peak at 3746 cm-1 that decreased with increasing NH3
or H2O pressure and a hydroxyl peak that was red-shifted due to hydrogen
bonding with the NH3 or H2O gas species. Increasing temperature caused
increased desorption of the NH3 or H2O gases, therefore the isolated hydroxyl
peak increased with increasing temperature at constant gas pressures.
The experiments confirmed that TEOS reacts with the isolated hydroxyls
due to the absence of the isolated hydroxyl peaks and presence of ethyl
C-H vibration features in the spectra. Heats of adsorption were determined
in each case through different methods. The measured heats of adsorption
of NH3 on clean silica ranged from –8 kcal/mol to –11 kcal/mol. The
measured heats of adsorption of H2O on clean silica ranged from –8 kcal/mol
to –14 kcal/mol. The measured heats of adsorption of NH3 on TEOS-reacted
silica were around 11 kcal/mol.
