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UW ChE Student Presentations

Tuesday, May 13, 2007

The following students will give presentations at the May 13, 2008 meeting of PSAIChE:

(The students are all currently seniors in Chemical Engineering at the University of Washington)

Danny Kress

Improvement of Fiber-Reinforced Composites

Composites represent an important new class of materials made by imbedding fibers into a polymeric resin.  They are often lighter and stronger than other materials of equivalent volume, and are being used in the production of new generations of airplanes, military protective gear and sporting goods, among others.  Their properties depend not only on the bulk properties of the resin and the fibers, but also on the adhesion between the fiber surfaces and the matrix, and arrangement of the fibers within the matrix.  Surface treatment of fibers to improve adhesion is a common method of improving composite strength. Our research has been exploring different surface treatments of glass fibers, specifically dendrimer coatings, that help improve adhesion and potentially decrease unwanted inter-fiber effects. 

Aaron Loe

Electrochemical Printer Model

A mathematical model was formulated and solved for an electrochemical printer.  The model involves multiple chemistries, for Ni2+ and Cu2+, and used the Nernst-Planck equation with electroneutrality and the Navier-Stokes equation.  A key parameter is the fly-height, the distance between the micro-nozzle and substrate, and this changes in time due to the electrochemical process.

Álvaro Presenda

 Stability of S-Layer Proteins for Electrochemical Nanofabrication

Crystalline cell surface layer proteins (S-layers) can be used in electrochemical fabrication to create nanoscale arrays of metals and oxides on surfaces so long as the proteins maintain their long-range order during processing. We have explored the stability of the HPI layer protein (the S-layer protein from the microorganism Deinococcus radiodurans) adsorbed onto platinum surfaces after immersion in sulfuric acid or sodium hydroxide electrolytes ranging in pH from 0 to 14 over time periods ranging from 1 to 1000 s. Topographic data obtained by atomic force microscopy (AFM) was used to characterize the protein stability, judged by its retention of long-range order after immersion. The compiled data revealed that, under these solution conditions and in this environment, the HPI layer protein has a dose-dependent structural stability "envelope" in the acidic range from 1 < pH< 4. The protein retains its long-range order up to 1000 s from pH 4 to 11, and has a sharp stability edge between pH 12 and 13. Interestingly, the more stringent requirement of stability (i.e., retention of long-range order) defined in the context of electrochemical fabrication for this protein narrowed the window of stability in pH and time when compared to previous stability studies reported for this protein.

 Marc Yamamoto

Electrostatics in Nonaqueous Media

Fine particles dispersed in an aqueous medium usually develop a charge at their surfaces by a variety of different mechanisms.  A cloud of ions of opposite charge (counterions) surround the particles, producing what is called an electrical double layer.  The overlap of the counterion clouds as particles produces electrostatic repulsion between the particles and the primary mechanism for their stabilization against aggregation.  In contrast, the possible importance of electrostatic effects in the stabilization of nonaqueous colloids against aggregation has long been the subject of controversy.  Part of the problem is the difficulty of measuring double layer properties in such systems because ion concentrations are so low.  Recently new instrumentation, based on phase angle light scattering, has become available that allows the determination of the very small electrophoretic mobilities expected in these systems. The present work uses this technique to investigate the properties of cerium oxide nanoparticles dispersed in dimethyl sulfoxide, and it is found that robust double layers exist in this system and can be used to control aggregation behavior.

Schedule

Meeting Location  

Ivar's Salmon House (Lake Union)

(Due to limited room capacity, only the first 60 reservations will be accepted.)

(please do not contact the restaurant for reservations or cancellations)

Take 1-5 to N.E. 45th Exit (#169). Go east, toward the University of Washington,

and turn right at Brooklyn Avenue. Follow Brooklyn to Pacific Street and turn

right. At stop sign, turn left. The Salmon House is one block further, on the

left, at 401 N.E. Northlake Way.

Menu

Buffet Including:

Meeting Reservation Form

Cost

NOTES

(Due to limited room capacity, only the first 60 reservations will be accepted.)

1. Please make reservations or cancellations by the Friday before the meeting.

2. Please pay by check payable to Puget Sound Section AIChE, or bring exact change.

3. For reservations:  

4. You can cancel by calling by noon of the Friday before the meeting. Dinner reservations "no-shows" will be billed!!