[Sci-all-l] Three Physics Talks Next Week

[Luc Peterson]

The physics and astronomy department would like to invite you to  
three lectures next week by  candidates for next year's visiting  
assistant professor position. A question/answer session will follow  
each lecture at 3:00 pm.

Thank you.

-Luc Peterson, on behalf of the Physics and Astronomy Majors' Committee

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On Monday, 4/24/06 we have Brice Smith who will be giving a talk at  
2:00pm in Sanders Physics lounge on
Environmental Radioactivity: Modeling the Risks

Over the last sixty years, a large number of sites have been  
contaminated with naturally occurring and human made radionuclides.   
While by far the largest sources of this contamination has been the  
production of nuclear weapons and nuclear power, a number of other  
activities have contributed to the problem as well.  The question  
that we now face is to determine how clean is clean enough when these  
sites are remediated.  In order to make that determination a number  
of computer codes are used to model the transport of radionuclides  
from the soil to people.  One of the most important of these is the  
ResRad code developed at Argonne National Laboratory.  This talk will  
introduce the conceptual model used by ResRad to model the transport  
of radionuclides through the environment and address the areas where  
more sophisticated treatment may be required to more accurately  
represent the physical processes governing radionuclide transport in  
the real world.  In addition, the models used to determine the impact  
of radiation exposure in ResRad are based on methods more than 30  
years old.  How these models of radiation risk may be updated to take  
into account the greater radiosensitivity of women and children and  
the possibility of non-cancer effects on the embryo/fetus will also  
be discussed.

On Wednesday, 4/26/06 we have Paula Fekete , at 2:00pm in Sanders  
Physics lounge on:
Nanostructures and Mesoscopic Physics


A talk given by Paula Fekete
Department of Physics, City University of New York,
Hunter College, 695 Park Avenue, New York, NY 10021


Miniaturization has transformed our daily lives by making possible  
mass production of inexpensive, integrated electronic circuits made  
up of devices and wires with sub-micrometer dimensions.  These  
semiconductor structures are now omnipresent, controlling everything  
from our cell phones to our toasters.  It seems likely that  
technology will reach a new, yet smaller scale in the near future,  
the nanometer scale.  The development of such novel devices requires  
a deep understanding of the physics of mesoscopic structures,  
structures with dimensions much smaller than the mean free path of an  
electron, which is the distance that an electron travels before its  
initial momentum is changed.  These systems form a bridge between  
macroscopic systems governed by classical physics and microscopic  
systems governed by quantum physics.  This talk reviews some results  
of experimental research into mesoscopic devices and outlines some of  
the theoretical framework for understanding their behavior.
On Friday, 4/28/06 we have Samuel Amanuel, at 2:00pm in Sanders  
Physics lounge on:

Curing Reaction Behavior of Nano Scaled Phenolic Resin Solution:  
Thermal and Molecular Vibration Studies

Samuel Amanuel* and Vivak M. MalhotraÝ
Department of Physics
Southern Illinois University, Carbondale, IL 62901-4401

There is a considerable body of data which shows that physical  
confinements of polymers at nanoscale (< 125 nm) alter their  
thermodynamic and dynamic properties as manifested by the change in  
their glass transition temperature relative to bulk state.  However,  
of equal practical importance is how nanoscale physical confinements  
affect the curing behavior of polymers.  To understand how such  
confinements affect curing properties, we undertook differential  
scanning calorimetry (DSC) and infrared (IR) measurements on phenolic  
resin physically confined in various pore sized (<125 nm) silica  
particles at 323 K < T < 493 K.  Our DSC results indicated that the  
curing reaction temperature of the phenolic was elevated due to  
physical confinement.1  In fact, the curing temperature inversely  
scaled with the decreasing pore size.  In addition, the curing  
reaction enthalpy showed a local minimum with respect to the pore  
size.  Our recent vibrational measurements not only supported our  
observation that a nanoscale confinement increased the curing  
temperature but also the confining surface may have a catalytic  
effect on the curing behavior of phenolic.
1. S. Amanuel and V. M. Malhotra, J. Appl. Polymer Sci. 99, 3183 (2006).