Tuesday July 24, 2007

Today we prepared solutions with various concentrations of surfactant from a 5% stock solution of Dodecylsulfate, Sodium salt, 99% (the surfactant) in water. Jaingshui prepared the stock by dissolving 22.5 g of the salt in 450 ml of water. We prepared a 1/10 dilution of the stock to create a 0.5% solution, then a 1/10 dilution of that to prepare a 0.05% solution. By mixing 18 ml of 0.05% with 12 ml of water, we prepared a 0.03% solution.


We then set up the tensiometer to determine the surface tension of the water/surfactant solution. The purpose of a surfactant is to reduce surface tension. We received a surface tension reading of 61.



After lunch was the Russell group weekly meeting. Dr. Russell set the sequence of presentations, then spoke with individual group members about their progress, expenditures, and references. He spoke with some of the newer PhD candidates about the upcoming cumes. First and second year PhD candidates must take exams (cumes) as part of their program. The exams are offered on the second Saturday of the even numbered months, and consist of six questions; two chemistry, two physics, and two engineering based. PhD students must answer four of the six questions at each session. The students must pass four Cumes in a row, or five total.

Jiangshui was first to present a paper, which was titled "Capillary Origami". A drop of water placed on a nanomembrane causes the nanomembrane to adhere to the surface of the droplet and conform to its shape in a manner that uses the least amount of energy. Be sure to watch the video of the folding process in this website.

The second presentation was by Jodie, and was a synopsis of her PhD dissertation at M.I.T. entitled "Ion Transport-Electrochemical Energy: How Do Ions Transport in a Polymer Electrolyte." Her research focus was trying to improve the generating power of batteries; specifically to develop a medium to sit between the anode and cathode that transported ions like a liquid but has the mechanical properties of a solid. Third to present was Tomomi, who is testing various polymers that may improve the productivity of fuel cells. Currently, Nafion is the main conductor in fuel cells, but it is expensive to produce and does not perform well at high temperatures. As Dr. Woudenberg discussed in his dissertation defense on July 17, this is an area of extensive research and study. There is a great deal going on here at UMass to improve energy production by both fuel cells and photoelectric cells to reduce our dependence on fossil fuels. Jodie also made the final presentaton of the day, discussing piezoelectricity. Again, the idea of generating power without generating pollutants or dependence on foreign production is receiving attention.