I’ve been trying to convince myself that the black holes seen in endothelial cells that we’ve been calling vacuoles are actually vacuoles. The first set of experiments involved staining cells with TAMRA, a fluid-phase marker which should get pinocytosed into vacuoles. Although there has been co-localization between ‘black spots’ in the calcein channel and red…
Recently, I have been trying to pass 5 nm, 10 nm, and 15 nm gold through untreated, carbonized, and ozone/carbonized membranes. These experiments were done in the pressure cell with fresh samples. I used a 1:1 dilution of Au stock and DI water. To wet the membrane I placed a 40 uL drop of water…
Last week, I used a 6-inch thermocouple wafer to profile the temperature uniformity (outside the susceptor) in the RTP. I measured four points: center, front, back, and center-right (positions relative to the RTP door e.g. front means closer to the door). The center-right position was chosen to verify side-to-side uniformity of the lamps. Below is…
Back a year or more ago, we had analyzed the EO flow rates from pnc-Si and determined that the flow was much higher than any other material. We then went on to try to calculate the zeta potential using the Helmholtz-Smoluchowski equation: We figured out the velocity of the fluid, v, from our flow rate…
Ag/AgCl electrodes are used overwhelmingly in streaming potential and sometimes in electroosmosis. The benefit of using Ag/AgCl in electroosmosis should be less gas generation and the ability to make an enclosed pump. Here is some information on my attempt at Ag/AgCl EO. .2mm silver wires were coated with AgCl using protocol. Electrodes were immersed in…
All electrokinetic phenomena are connected by a form of the Helmholtz-Smoluchowski equation. In the case of electroosmosis, the equation can be written as follows: where v is the velocity (in m/s) of water flow through the pores, epsilon the permittivity, E the electric field, zeta the zeta potential, and eta the viscosity. Since we do…
During the past few weeks, I have been experimenting with different array setups for diffusion. I have been working with BSA, but I will move to APOBEC3G protein once the arrays Barrett designed are finished. All of the pnc-Si arrays used were treated with UV-ozone. Treating with UV-ozone cleans the surface and helps prevents the…
I’ve tested several membrane types with the streaming potential apparatus in order to calculate zeta potential. Here are the results: All materials in the above chart have negative zeta potentials. Pnc-Si seems to have the highest overall potential, followed by PES then cellulose. Cellulose is prone to cracking and bursting at pressure above 7 PSI….
Chris asked me to do some scans of samples last week but I didn’t have time to get to them. I was able to scan them today since I was setting the AFM up for my class anyway. I took 1um square scans (512×512) at 1Hz for all samples. The target and set point voltages…
Today I tried to pass 5 nm gold through three different membranes with similar cut-offs but distinct mean diameters and porosities. All the samples I used were ozoned yesterday and tested for water permeability. Based on the absorbance measurements, it seems that the 5 nm Au passes through 582 and 558 but not the carbonized…