It’s been a slow few weeks so I combined the updates into one post.
Poly tested two MnCaO and two MnVO plates but didn’t report on the results (not good?). They also wanted to try a different method of pre-cleaning plates to allow for better results, so they went to the Atwater lab and used their plasma cleaner for 30 seconds. This should get rid of any extra debris and material on the plates. They spotted Fe(NO3)3 to test as a control.
Beckman Group 1 re-epoxyed their plate from last week, whose epoxy binding had come apart in the sodium sulfite solution after they let it dry for well over five minutes. They will let the epoxy sit for about an hour before they test it again. They are also baking the plate that they previously spotted. Group 2 is testing a plate with chromium (III) nitrate. They are also making a new plate with chromium and zinc with a ratio of 1:1. Group 3 made a new 0.03 M iron nitrate solution since they were running low. They also set up last week’s plate for testing, and will test it after the teams that are in line for testing. Group 4 has discovered several inconsistencies that may have played a role in how their plates turned out. They had set up a plate last week for testing this week – which was UV-tested for five minutes – so they planned to test the plate today. However, the five-minute and one-hour treated plates had much better consistency in their spots than the ten-minute plate; they switched to a new micropipette for the ten minute-plate with a thinner tip, which may have resulted in discrepancies. Moreover, the iron (III) nitrate solution that they used for the four plates has become cloudy, so they will have to remake the solution and UV treat a new batch of plates starting next week, using both the new solution and the new micropipette. Despite this, they will still follow through with testing the plates they already have, including the thirty-minute plate, which has air dried but will needs to be fired.
San Marino Blank Team Tested the new nickel-copper plate. Spots were clean and had minimal coffee ring effect. Iron spots are slightly flaking. Overall, the least flaking of all the plates done so far! Plate did not flake much when placed in KOH solution. All tests: every area (spotted and unspotted) had blue peaks, with exception of the two Cu control spots. Results are inconclusive (perhaps except for the flat Cu spot)
Made new plate (total volume each spot is 10 microliters):
0.1 M Cu(NO3)2 + 0.1M NH4VO3 (2.5:7.5) – Turned bright yellow, (5:5), (7.5:2.5)
0.1 M Ni(NO3)2 + 0.1 M NH4VO3 (2.5:7.5), (5:5), (7.5:2.5)
0.1 M Fe(NO3)3 control
0.05 M NaVO3 (sodium metavanadate)
0.1 M NH4VO3 (ammonium metavanadate)
Green Team tested the plate made on 1/22, got no significant peaks, probably due to the low temperature (~375℃) at which it was fired. Remade the plate but got deep coffee rings this time with not much substance in the middle. Worrisome since it could mean that the light is not actually hitting the particles and only faded parts of the particles. This might mean that the testing on this plate was flawed. Results were as usual— all blue with negligible difference even when the concentration of a material multiplied by ten. However, the substances are in a 1:999 ratio and a 1:99 ratio, so it seems like these materials aren’t actually contributing at all. The plan for next week is to plate a control of copper and iron to see how hydrogen peroxide layered over the spots influences the results and also see if the materials are good light absorbers or not.
Earlier in the week, they plated 0.10M Fe(NO3)3 and 0.10M Cu(NO3)2 in a checkerboard pattern as a control. They aimed to observe the effect of adding Na2SO3 to our NaOH testing solution. The plate reached a temperature of 500℃ and the Cu spots were solid, dull, and black. The Fe spots had a faint red/brown coffee ring, with shattered metallic bits in the center. These bits flaked off once the plate was inserted into the NaOH solution. Initially tested the control plate in the regular NaOH solution. With no bias applied, Scan #1 displayed very low Cu spots, while the Fe peaks and background dark current were at roughly the same level. After applying a voltage of 0.05V, similar results were observed. Subsequently, applied a voltage of -0.05V. This time, the Cu spot peaked, with the dark current on the same level as the low Fe. With a voltage of -0.1V, the results were the same, except the dark current increased slightly.
They then replaced the NaOH solution and added 0.1 mol of Na2SO3 to the 100 mL of NaOH solution. With no bias applied, the Fe peaked again. The Cu and dark current remained at the same level. With 0.05V applied, the dark current increased slightly. Just before -0.05V could be applied, the voltmeter ran out of battery and had to be replaced. The dark current briefly read 0.1. At -0.1V, the dark current was -0.3. The Cu spots peaked this time, with the dark current significantly higher than the low Fe spots.
With the addition of Na2SO3, the peaks seemed to decrease in height, possible as a result of the plate spending a long time in the solution. With a higher applied voltage, the peaks seemed to return to normal. When applied voltage was reversed, it was that the peaks flipped, with Cu now higher than Fe. Whether or not they expected this outcome depends on how the SEAL program interprets negative values…