Part I: Producing X-rays from adhesive tape
A Collaboration with Johnny Lu
Building our X-Ray source:
While we could have purchased a standard X-Ray tube as an X-Ray source… it seemed kind of scary and we decided it might be more fun to attempt our own X-Ray source using scotch tape in a vacuum. Inspired by research done in 2010 at UCSD by Moses Marsh and the Shpyrko Group.
The X-Ray producing effect is related to:
- triboluminescence: the emission of light when a material is crushed, rubbed, scratched, or pulled apart.
- Diffuse mechanical energy somehow concentrates huge charge densities over short time scales, resulting in high energy radiation during discharge.
- At 1atm, it takes 50mW to peel tape at 3 cm/s.
- In vacuum, it takes an extra 3mW. Of this, at least 0.2mW goes into accelerating electrons to 30 keV, generating an average X-ray power of 2 nW. The power going into visible triboluminescence is 10 nW. –Shpyrko Group
We fabricated a winding mechanism from laser-cut acrylic and a high torque 24v gearhead DC motor. Our motor pulls approximately 9cm of tape per second, just slightly slower than the build at UCLA.
Initial testing revealed clear signs of triboluminescence seen here, though no confirmation yet of X-Rays. We used an X-Ray phosphor (Gadolinium Oxysulfide: Terbium) as a visual indicator, but so far we have not seen any phosphorescence. We have only recently acquired a detector capable of reading X-Ray radiation, hopefully this will lead us in the right direction.
We have so far only been able to bring our current vacuum chamber down to about -98 kPa against standard atmospheric pressure, which is about 3 magnitudes weaker than where UCLA was at (.0001 Torr). We believe we can’t go any lower with our current air-driven pump. We need to move to a multi stage oil-diffusion pump if we plan on getting a better vacuum… possible complications: vessel integrity.
|pressure (Torr)||pressure (Pa)|
|Atmospheric pressure||760||101.3 kPa|
|Low vacuum||760 to 25||100 kPa to 3 kPa|
|Medium vacuum||25 to 1×10−3||3 kPa to 100 mPa|
|High vacuum||1×10−3 to 1×10−9||100 mPa to 100 nPa|
|Ultra high vacuum||1×10−9 to 1×10−12||100 nPa to 100 pPa|
|Extremely high vacuum||<1×10−12||<100 pPa|
|Outer Space||1×10−6 to <3×10−17||100 µPa to <3fPa|
|Perfect vacuum||0||0 Pa|
Part II: The Effects of Ionizing Radiation On Plant Growth and Mutation
Our Exposure Candidate: Pumpkin Seeds
Using a standard dental X-ray device we will expose pumpkin and sunflower seeds to varying levels of radiation (most dental X-ray devices deliver around .005 mSv per exposure – equivalent to about 3 days of background radiation or a long airplane flight). We chose pumpkin seeds on the recommendation of Dave Jackson from Cold Spring Harbor genetics lab. Pumpkin and squash are fast growers and we concluded that if we are to get any growth in the amount of time we have… it had better be fast!
Powerful ionizing radiation such as hard X-Ray and Gamma radiation has a destructive effect on DNA… essentially tearing it apart and causing it to form mutations. This is how cancer growth happens when exposed to radioactive material. We speculate that if our X-Ray source has any effect at all it will probably be totally inhibitory or sterilizing… that is: nothing will grow.
Part III: The Effects of Aqueous Ferro Fluid and Magnetic Fields On Plant Growth
As a bonus (and possible plan B) we have finally acquired all the necessary chemicals and equipment to synthesize aqueous (water based) ferro fluid, with the goal in mind to inject it into living plants to see if it, in addition to a magnetic field, has and effect on the growth of the plant.
Aqueous Ferro Fluid Synthesis
We are preparing the ferro fluid by iron oxide co-precipitation from auto-catalytic reaction of ferrous (Iron(II) Chloride Tetrahydrate) and ferric (Iron(III) Chloride Hexahydrate) salts.
We have yet to make a decision on what to use as a surfactant, the substance that coats the magnetite nano-particles, helping to keep them in suspension. tetramethylammonium hydroxide has been used, but its potential toxicity here with plants makes it a bad candidate. We are considering citric acid, oleic acid, and linoleic acid as non-toxic substitutes.
If synthesis is successful we plan to begin injections immediately into pumpkin and sunflower seeds in two groups; one with magnetic field exposure, and one without. Again pumpkins and sunflowers were chosen because they are fast growers. We will maintain a non-injected control group and log growth from germination.