RM's+Week+of+October+29

RM's Logbook


 * Monday, October 29, 2007**

Today, I scanned through some introductory AFM websites that DH e-mailed me when she was browsing STM websites. In this reading, I came across “van der Waals” forces, which I learned last year in chemistry. I didn’t quite remember what they were, so I did a quick search on [|Wikipedia]. They are actually the attractive forces between molecules that arise from covalent bonding. They are also weaker than the forces arising from chemical bonds. I went over a few more details, of which I will spare this logbook. Anyway, for the remainder of the period, I’m going to review the ND lab safety rules (it’s an enormous packet!).


 * Tuesday, October 30, 2007**

I'll be going to ND today, again, after school. Today, I had to fix a few things on this logbook (organizing, updating, creating links, etc.). However, I also read through the link DL sent us on the Siemens Competition. It's really amazing what some of those students researched during their high school years. In a couple of weeks, the regional finalists will present at ND- I'm planning on attending the competition to see the various projects.

At ND, AL took images, none of which were satisfactory because no DNA was located. However, streaks appeared on the sample surface- we thought it might be due to its spraying by nitrogen gas. I also turned in my ND lab safety agreement form.


 * Wedensday, October 31, 2007**

There are no plans, today, to go to ND. The next time I go, however, I want to learn what factors can affect the APTES solution and the deposition of DNA on the monolayer. I'm planning to ask Dr. Sarveswaran about the effects of temperature, inputting electric fields, and pH on how the DNA lands on the surface, or derive a hypothesis on how it would affect it. In a few minutes, AL and I will discuss AFM with DL.


 * Thursday, November 1, 2007**

I wasn't in class today, but rather at Stepan. I watched AL put together a couple of samples and after that was done, we went down to the AFM. There, I watched him set the AFM up. There was a problem with the tuning, and it ended up being due to a bad tip. So, I watched AL scan his APTES-soaked wafer without DNA under the AFM. Dr. Sarveswaran suggested that whenever we use our images in presentations, we should take images of the plain silicon wafer surface, the wafer with APTES, and the wafer with APTES and DNA to have a pictures of each stage for evidence of how the surface changes after APTES and the DNA are added.

I asked Dr. Sarveswaran about trying different methods to linearize the DNA. I asked about changing the pH, and she said that DNA is only stable within a certain range of pH. If the pH is too low, or too high, the DNA will linearize but it won't be stable. Regarding temperature, the higher the temperature, the higher the ability of DNA to move and linearize. Also, changing the amount of time that the DNA is soaked in APTES affects the results. The reason it is left in APTES for 10-15 minutes is that it forms a monolayer. If it is left in the APTES for a shorter amount of time, patches form, which wouldn't be conducive to research. If the wafer is left in the APTES for too long, many layers will form, and instead of the APTES acting as a positive, adhesive agent, it will not attract the DNA anymore, but repel it (I'm pretty sure that she said "repel"; I have to check that again. If she said something different, I will change this entry).


 * Friday, November 2, 2007**

Today is a shortened schedule (half-day), so I thought that this would be the opportune moment to update my logbook. I'm about to create a new page for next week and add a few links.

Week of October 22

Week of November 5