Computational Oral Presentations

Study of the Effects of Heavy Water on Acid-Base Equilibria

Fransbergen, Tiffany

  • Tiffany Fransbergen, Peter R. Tremaine*, Nelaine Mora-Diez*
  • Organization: Thompson Rivers University
  • TRU-CUEF, U-REAP, University of Guelph

Abstract: Many nuclear reactors in Canada are deuterium uranium reactors (CANDU). These Canadian-designed reactors use pressurized heavy water (D2O) as a neutron moderator and as the heat-transport fluid in the primary coolant system. Very little is known about the effects of heavy water on the acid-base equilibrium of chemical substances, thus this is an important area of study with important conceptual and technical implications. The strength of an acid in solution at a given temperature is determined by its dissociation constant (Ka). This work focuses on the theoretical determination of the pKa (pKa = -log Ka) values of a group of colorimetric indicators at very high temperatures and pressures in H2O and D2O. Density functional theory (DFT) calculations are performed using the B3LYP functional and the 6-311++G(d,p) basis set. Solvent effects are initially accounted for by means of continuum solvation models. This is a joint project with a group at the University of Guelph, who is working on the experimental determination of the values that we are attempting to predict computationally.

Visualizing the Chemistry of Climate Change

Genuis, Katrina

  • Katrina S. S. Genuis, Peter Mahaffy*, Brian Martin*
  • Organization: The King's University College
  • Funding: NSERC - USRA, CRYSTAL

Abstract: The translation of the fundamental chemistry of climate change into engaging, interactive learning resources is essential if undergraduate and high school students are to understand the challenges implicit in global climate change. The King's Centre for the Visualization of Science (KCVS) conducts multidisciplinary research to develop online visualizations of scientific processes. KCVS, in partnership with IUPAC, ACS (USA), RSC (UK), and UNESCO, is developing a suite of digital learning objects (DLOs) which illustrate the underlying chemistry of Earth's climate. My research has focused on two:
1. The IR Spectral Windows DLO demonstrates how certain molecules in the Earth's troposphere absorb Infrared (IR) Radiation in particular regions of the IR Spectrum. This interactive visualization allows users to select atmospheric greenhouse gas molecules and learn about areas in which they absorb and re-radiate outgoing IR radiation.
2. The Earth's Radiation Balance DLO demonstrates the four key factors that regulate a planet's radiation balance (incoming radiation, albedo, energy emitted, and greenhouse effect) and allows users to alter these factors, creating simulated planets with different climatic environments. These DLOs will play a key role in the development of online curriculum regarding climate change science, available to high school and undergraduate students and educators worldwide.

Nucleotide Complexes in YchF

Rosler, Kirsten

  • Kirsten Rosler, Hans Joachim Wieden*
  • Organization: University of Lethbridge
  • Funding: UofL

Abstract: YchF is one of only 8 known universally conserved GTPases and at this point its function is unknown. It has been classified as a member of the ATP sub family of OBG GTPases because it contains the conserved G domains, yet binds and hydrolyzes ATP more efficiently than GTP. GTPases have extremely diverse functions, from roles in protein synthesis, cell cycling and hormone signaling. One thing NTPases do have in common however, is the use of a Mg2+ ion in the binding of a nucleotide, in particular the Mg2+ ion is responsible for coordinating the phosphates of nucleotide. YchF is unique in that all available crystal structures do not have high enough resolution to prove the existence of Mg2+ ion in the biding pocket. In order to determine if YchF requires Mg2+ to bind adenine nucleotides dissociation constants were determined using pre-steady state and steady state kinetics. Dissociation constants for ADP in Mg2+ concentrations ranging from 0 to 20mM were all found to be approximately 10 micrometer. From these experiments it appears that YchF does not require Mg2+ to bind ADP. To confirm these experimental results, computational studies on an E.coli YchF homology model were performed. These studies have shown that the presence of Mg2+ destabilizes the base of the ADP, but stabilizes the phosphates.