Spring 2007 Graduate Student Seminar Series Kicks Off January 31

The first of the Spring 2007 Graduate Student Seminars will be Wednesday, January 31 at noon in Room 1005 of the Beckman Institute. The seminars are open to the UIUC campus. Lunch will be served.

Speakers and abstracts are listed below:

Computational Studies of Nuclear Pore Complex Transport Dynamics
Timothy Isgro (TCB)

The nuclear pore complex is responsible for regulating transport into and out of the cell nucleus. It allows for communication with the rest of the cell and prevents the transport of molecules not destined to enter or leave the nucleus. Small molecules may pass through the pore unhindered, but for larger ones, transport is highly selective and controlled. Large molecules must first associate with a chaperone protein, called a transport receptor, which is recognized by the nuclear pore. However, the mechanism by which the nuclear pore allows transport receptors to be transported across the nuclear envelope, while restricting the passage of other molecules, is unknown. But the role of a specific set of nuclear pore proteins containing amino acid FG-repeats has been established as essential in the transport process. For the first time, the computer has been utilized to perform extensive sampling of the dynamics of transport receptor:FG-repeat interactions in atomic detail. The result is a view of interactions between the pore and its transport receptors which both confirms previous experimental data and provides evidence for new interactions at a more detailed level than previously realized.

Carbon Nanotube Optical Biosensors for Detection in Single Cells
Daniel A. Heller (NB)

The intrinsic fluorescence of single-walled carbon nanotubes exhibits an environmental sensitivity which can be employed in living systems for optical detection of important analytes. The bandgap emission of nanotubes, between 800 and 1600 nm, is photostable under continuous excitation and penetrates biological media which can absorb or scatter light at visible wavelengths. Complexes of nanotubes encapsulated by DNA oligonucleotides were developed to detect conditions of DNA alkylating activity and oxidative damage. The complexes exhibit a concentration-dependent red-shift in emission energy upon binding to alkylating agents such as nitrogen mustards and platinum compounds. The nanotubes continue to emit within the cell environment, transmitting information in real-time from live tissue. Nanotube-based biosensors will be employed in kinetic studies of drug interaction within single cells and live tissues.

Effect of Confined Optical Phonons on Hole Scattering in Silicon Nanowires
Mueen Nawaz (CE)

As components of devices shrink to the nanometer scale, their electronic behavior deviates from that demonstrated in bulk (regular) devices. Quantum effects begin to play a more prominent role in the transport of charge carriers in nanowires. As the diameter of wires becomes smaller, phonons are no longer treated as continuous entities, and certain selection rules apply when calculating carrier scattering due to them. In this talk, the continuum model of confined optical phonons is presented, along with its scattering effects on holes in silicon nanowires. A comparison is made with the scattering rates calculated by using the bulk model for optical phonons. Understanding phonon scattering is essential in understanding how charge carriers flow in such nanowires.