Competition Winners / Abstracts - Physical Sciences
Physical Sciences 1 - 1st
Biocompatible Luminescent Silicon Quantum Dots for Imaging
of Cancer Cells
By Ngozi Agbasionwe, University at Buffalo
Luminescent silicon quantum dots (Si QDs) have great potential
for use in biological imaging and diagnostic applications.
To exploit this potential, they must remain luminescent and
stably dispersed in water and biological fluids over a wide
range of pH and salt concentration. There have been many challenges
in creating such stable water-dispersible Si QDs, including
instability of photoluminescence due their fast oxidation
in aqueous environments and the difficulty of attaching hydrophilic
molecules to Si QD surfaces. We report the preparation of
highly stable aqueous suspensions of Si QDs using phospholipids
micelles, in which the optical properties of Si nanocrystals
are retained. These luminescent micelle-encapsulated Si QDs
were used as luminescent labels for pancreatic cancer cells.
This paves the way for silicon quantum dots to be a valuable
optical probe in biomedical diagnostics.
Physical Sciences 1 - 2nd
Analysis of Some Near-Infrared Spectra of C2Br
By Elizabeth J. Millings, Suffolk County Community
In combustion chemistry, the C2H molecule has been studied
extensively because it is an important intermediate and provides
an example of the breakdown of the Born-Oppenheimer approximation.
A related molecule, C2Br, supplies a different view of the
Born-Oppenheimer breakdown. Previously, only computational
studies have been reported regarding C2Br. Its energy states
and spectra were theoretically determined, and a model equation
was developed to describe its rotational energy levels. Recently,
a spectrum of C2Br was accidentally detected at Brookhaven
National Laboratory. In this project, the spectroscopic data
were further examined in an attempt to confirm the assignments,
determine the rotational constants, identify spectral lines
corresponding to the two bromine isotopes, and identify the
band origins. To accomplish this, a LabVIEW computer program
was developed and used to calculate the energy levels and
predict spectra, which were then compared to the experimental
near-infrared (NIR) spectra. The error between the data and
the calculations was minimized by adjusting the modeling constants
and testing possible assignments. A simulated spectrum was
created with each new calculation enabling a set of “best
fit” values to be determined.
Physical Sciences 2 - 1st
Synthesis and Characterization of Copolymer-templated Periodic
Mesoporous Methylenesilicas and Phenylenesilicas
By Abhishek Roka, College of Staten Island
Surfactant-templated periodic mesoporous organosilicas (PMOs)
have received much attention as well-defined periodic inorganic-organic
hybrids, catalyst supports, hosts for nanoobjects and media
for immobilization of biomolecules. In some applications of
PMOs, it would be beneficial to enlarge the pore diameter
beyond 10 nm, which is a typical limiting pore size value.
Recently, it was demonstrated that this goal can be achieved
by performing the block-copolymer-templated synthesis of PMO
with spherical pores at low temperature (5-15 °C) in the
presence of aromatic hydrocarbon (trimethylbenzene) as a micelle
expander, following the method reported earlier for large-pore
ordered mesoporous silicas. The current project is intended
to further explore the opportunities in the synthesis of large-pore
PMOs with methylene and phenylene bridging groups and with
large cylindrical pores using micelle swelling agents. The
work in progress includes:
- Attempt of synthesis of large-pore methylene and phenylene
PMOs in the presence of different hydrocarbons and under adjusted
conditions, and characterization of the products.
- Optimization of block copolymer ratios, and temperature
variations in order to further increase pore diameter to a
Physical Sciences 2- 2nd
An Electron Paramagnetic Resonance (EPR) Study of Metal-Site
Dynamics in Amino Acids: Copper Hopping in Cd-Histidine Crystals
By Brenda Marmol, SUNY College at Old Westbury
To understand copper dynamic behavior in a simple biological
system, EPR spectroscopy was applied to crystalline samples
of a model histidine complex. Dynamics were detected by measuring
the EPR spectra as a function of temperature. At low temperature
(<160K) the spectra displays two copper patterns, related
by a crystallographic two-fold axis. At high temperatures
(>230K), the EPR spectrum shows a single copper species.
EPR hyperfine component line-widths were fit at the various
temperatures in order to determine dynamic characteristics.
These results are interpreted using a model where copper atoms
hop between two binding sites at low temperature (Tc ~190K).
Below Tc, the copper is frozen in one of the two, symmetry-related
sites. As Tc is exceeded, the two patterns collapse into an
“averaged” spectrum. We propose that the copper
is bound to only one of the symmetry related histidine molecules
at temperatures lower than Tc, and at higher temperatures,
the copper ion hops across the two-fold rotation axis.