User:Brian P. Josey/Notebook/2011/02/17

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Qualitative Experiments, and Magnet Comparison
I finished assembling the electromagnet today, and I wanted to test it. To do this, I created three flow cells containing ~10 uL of 1:10 ferritin dilution in water. I put one of each into the neodymium magnetic horseshoe, and the Lego electromagnet, keeping the third as a control. Here is a picture of the three flow cells side-by-side right after I made them:



I left the control flow cell sitting out on a table to serve as a comparison for the other two flow cells. I have noticed before that the flow cells will often dry out after an hour, leaving a kind of misty deposit on the glass. Generally, it also takes a while for the magnets to move the ferritin, and before I have compared the areas of highly concentrated ferritin with this misty deposit. When ferritin does gather near a magnet, the deposit is clearly darker, and brown in color, while the misty is just smokey. The control then serves as a background comparison between the depositing of the ferritin across the whole flow cell, versus the collecting of ferritin in a specific spot. Here is the control after sitting out for an hour:



As per usual, I placed the flow cell in the neodymium horseshoe magnet so that the tip of the cone was touching the thin cover glass. This serves as a direct comparison for the electromagnet with the best case senario. After letting it sit against the magnet for an hour, it looked like this:



As I expected, the flow cell had dried a little, but there was a slight darkening near the tip of the magnet. I had placed the tip near one of the tapped edges of the flow cell, and a plume, think erupting volcano, of brown colored ferritin streaked across the flow cell toward the other side. This is a typical result, indicating that the ferritin is still viable and potentially magnetic.

For the last flow cell, I put it inside of my newly constructed electromagnet, using the slip that I especially created for it. I then connected the magnetic wires, with aligator clips, to the connection wires from the current supply. I then passed a current of ~1 A through the wires. I did not measure the properties of the current with a multimeter, however. After an hour, it looked like this:



Clearly, something went wrong if the slide is still in the electromagnet. If you turned the electromagnet just slightly:



Despite all the time I spent on this electromagnet, I was brought down by a simple fact that I should have remembered: a very long strand of wire has a high resistance. Because of this resistance, the wire was hot to the touch, and over the hour that I had it placed in there, the plastic melted from the heat. However, despite this set back it did yield some interesting results. The first being that it did not succeed as well as neodymium does. In the flow cell the deposit is a slow and steady gradient to each side with the wires, but it is not dramatic. It would be incorrect to assume that it would be as clear as the neodymium magnet, but I feel like something more should have happened for it to be clear that the electromagnet worked well. At this point, comparing it side by side to the control, I would have to say that this magnet allows for a greater likelyhood of directing ferritin, but it is still not as great as the neodymium.


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