Friday July 20, 2007

Efren and I arrived at Conte by 7:30. He set up the X-Ray Reflectometer while I spin coated some films.


We then placed one of my specimens in the reflectometer to measure the thickness. We both caught up on our blogging during the 90 minute processing period. The data was just OK...we only got three consistent waves in a row, and there should be five in a row to get a good measurement of film thickness. We calculated the thickness to be about 100 nm thick, which is thicker than either Jaingshui or Dave get ( about 86 nm). The second slide was processed, but this time we got NO data...I put the specimen in backwards, so there was no film on the slide, just glass. Sheesh! There seem to be an infinite number of ways to mess up.

The normal Friday noon lunch for R.E.T.s (us) and R.E.U.s (undergrads doing research) was held, followed by two presentations by doctoral candidates. Kate was first to present; she received her undergrad degree at RPI and is working with the Lesser group on improving the environmental resistance of PBO. PBO replaced Kevlar as the primary constituent of bullet-proof gear because it has a higher tensile strength than Kevlar and is lighter in weight and simpler and less expensive to produce. It has failed, however, after prolonged exposure to UV light and moisture. The project is hoping to develop a polymer to coat the PBO that will confer UV and moisture resistance to the substance without reducing tensile strength.

The second presentation, by Simon, was entitled "Novel Hybrid Polymers Incorporating Carboranes as Pendant Groups". Simon is a fourth year PhD student approaching the end of his work. A carborane is an icosohedral cluster with Boron and Carbon integrated in the structure.

These structures are used in Boron Neutron Capture Therapy; the structures are incorporated into tumor tissues then bombarded with neutrons. The result is site specific, isolated radiation therapy. The carboranes accumulate in the tumors because of the high vascularity of tumors and the increased "leakiness" of the tumor capillaries because of decreased cell to cell junctions (a function of rapid angiogenesis). While tumors display a high rate of angiogenesis, they do not show an increase in lymph vessel proliferation. As a result the carboranes enter the tumor but are not drained out, therefore they accumulate there. Carboranes that do not accumulate in the tumor are cleared from the blood by the kidneys and excreted. The accumulated carboranes are then excited by a neutron beam aimed just at the tumor. More on carborane structure can be found here.

The remainder of the day was spent measuring thicknesses of films and measuring wrinkle patterns obtained on Thursday.