STUDENT RESEaRch SympoSiUm 2010 - Graduate and Research ...

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reach the tumor cells. Specifically, azaspirene blocks the unique
chemical signal sent out by tumors to attract more blood cells, but
does not inhibit other healthy red blood cell growth in the body
involved in blood vessel growth and wound repair. The result will
be that the cancer cells will begin to starve and consequently their
growth will be inhibited. Knowledge about the biological properties
of azaspirene in cancer-biology will help provide clues for the
future generation of anti-cancer drugs for battling severe types
of cancer. Methods: Our synthetic methods used are based upon
a “Chiron approach”, a strategy which utilizes the appreciation
of chiral inexpensive molecules available from nature. Since we
have identified these chiral building blocks, the total synthesis
is thereby greatly simplified and economically viable compared
to other reported synthetic studies toward the azaspirene and
its pseurotin family. Results: A novel approach will be presented
using L-tartaric acid and/or D-malic acid as substrates. The
presented procedure allows us to initiate the synthesis with most
of the oxygen atoms already contained within the molecule and
evidently reduces the need to do oxidation reactions to create the
highly oxygenated molecule of azaspirene.
Session B-7
Poster: Geosciences
Friday, March 5, 2010, 11:30 am – 2:00 pm
Location: Montezuma Hall South
#198 11:30–1:00
A Seawater-derived Uranium Signature and Possible
Mechanisms of Crustal Contamination in Loihi Seamount
Galsses
Matthew Keyes, Geochemistry (U)
Aaron Pietruszka, Geological Science
Excesses of 234U relative to 238U (up to ~1%) have been discovered
in fresh volcanic glasses erupted from Loihi Seamount
using high-precision MC-ICP-MS techniques. Mantle-derived
basaltic lavas are expected to be in radioactive equilibrium for
234U and 238U upon eruption. In contrast, seawater has ~14%
excess 234U, and thus, represents the most likely cause of the
observed 234U-238U disequilibrium. The origin of the seawater
234U signature is unclear. The main purpose of this study is to try
to determine if the seawater 234U signature is related to crustal
contamination with seawater-altered rocks surrounding Loihi’s
magma chamber or if it represents contamination of the glass
surface due to interaction with seawater during or after eruption.
To test these possibilities, eight Loihi glass samples with a range
of (234U/238U) ratios (previously analyzed for their 234U-238U
disequilibria with only a brief cleaning in 2M HCl) were treated
with a multi-step leaching process (6M HCl, 0.5M oxalic acid-2%
STUDENT RESEARCH SYMPOSIUM 2010
H2O2, and 1M HCl-2% H2O2). In most cases, the (234U/238U)
ratios of the strongly leached samples are similar to the previous
unleached analyses. Thus, the leaching procedure failed to
remove the excess 234U from the samples. This observation suggests
that the 234U addition most likely occurred during crustal
contamination of the magma with seawater-altered rocks. A mixing
calculation between the (234U/238U) and 87Sr/86Sr ratios
of seawater and a range of uncontaminated Loihi magmas can
be used to further test this possibility. This calculation shows that
bulk addition of seawater cannot explain the low 87Sr/86Sr ratios
of the contaminated Loihi lavas. Instead, U must be preferentially
enriched in the seawater-altered rocks prior to crustal contamination.
This might be possible if seawater percolating downward
towards the country rock surrounding the magma chamber encounters
more reducing conditions (possibly due to the presence
of magmatic H2S), and U (unlike the fixed valence, alkaline earth
element, Sr) might precipitate if it is reduced from the soluble +6
state to the more insoluble +4 state.
#199 11:30–1:00
New Insight into the Greater Caucasus Mountain Range
Fold-Thrust Belt
Christopher Binter, Geological Science (U)
Robert Mellors, Geological Science
The Caucasus-Caspian region is an area of frequent seismic
activity. This is due to the collision of the Arabian and Eurasian
plates that produce constant earthquakes throughout the region.
Accurate determination of earthquake hypocenters is important
to understanding the tectonics of the area as well as the potential
seismic hazards. The standard method of earthquake location
relies on generalized velocity models to locate earthquakes. For
most instances this method is appropriate, however in areas with
strong local velocity heterogeneities such as the Caucasus this
can cause hypocenters to be inaccurately placed. To reduce scatter
in hypocenter determination, the double-difference algorithm
of Waldhauser and Ellsworth (2000) is tested. This method
locates earthquakes in clusters and seeks to improve the relative
location of events rather than the absolute location. In this
way active fault planes become more apparent because greater
emphasis is placed on accurately placing hypocenters relative to
each other. Through the use of this double difference method I
will evaluate if the Greater Caucasus mountain range fold-thrust
belt is thin (involving only the sedimentary cover) or thick skinned
(including basement) in nature. Thin-skinned thrust faults dip
at low angles (< 35 degrees) while thick skin thrust typically
possess dips of 35-45 degrees. Currently I am determining the
accuracy and precision of the double-difference algorithm and
its ability to provide new information on the Greater Caucasus
mountain range fold-thrust belt.