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Episode 12 – Laserbones

On this week’s show– Laserbones–Chris and Cameron discuss laser-3-D-Printed materials based on bones (lasers & bones), the use of cremated remains for synthetic diamonds (bones), and potential space mirror technologies made out of laser-trapped polystyrene beads (lasers)! We also have our first iTunes review!

crushed microstrutures

Compression tests on 3-d printed micro structures (source)

3:23  Article from The conversation.com titled “Scientists create bone-like material that is lighter than water but as strong as steel”

3:45 The paper was published in PNAS and is titled “High strength cellular composites with 3-D microarchitecture”

9:00 the structure of these materials are 3-d laser printed plastic that is then coated with Alumina (Al2O3).

14:00 what would you do instead of building structures out of this material? Chris would build indestructible bees.

15:00 how laser-sintered 3-d printing works (this is kind of cool)

19:50 we begin on a story inspired by an NPR piece, “From Ashes To Ashes To Diamonds: A Way To Treasure The Dead”  where a swiss company will take cremated remains and turn them into a diamond for you.

22:30 we talk about what dopants are used to color Al2O3 crystals like sapphire and ruby (we call the clear Al2O3 “sapphire” in the lab, but most people just know sapphire as the blue gem).

24:50 The materials science aspect of the topic, how synthetic diamonds are grown!

26:45 Oh no! we forgot to explain what a phase diagram was! check this out in the meantime https://en.wikipedia.org/wiki/Phase_diagram

28:00  for reference, the melting point of some steel is near 1500 C, which is much less than the 3000 C needed to form graphite with a direct transition (no catalyst or seed material)

29:00 just the CVD process for growing Diamond was patented by Apollo Diamond, not the CVD process in general, this is a very common technique!

32:16 newscientist.com  “Laser light makes ultra-light mirror out of tiny beads” and the accompanying paper:
“optical mirror from laser-trapped mesoscopic particles.”

34:09 Chris has an interesting story about mirrors used in solar cells! (you put one at the back, and it helps make solar cells collect more light and be more efficient)

36:25 back on topic!  they want to use laser-trapped polystyrene beads to create mirrors that are very light and useful for space telescope.

39:30 they are slightly “cheating” by holding the beads against a glass slide, and they are holding the whole thing underwater to help with cooling the beads and to help stabilize them

47:10 our very first listener feedback segment!!! Thanks!
48:30 and our very first correction!

 

Intro:  Open – Crying (Get Olde)
Baby Bones – Laura Stevenson and the Cans
Diamond Rings – Fake Problems
Black Mirror – Arcade Fire
Outro:  Dreams are Maps – The Wild (Dreams are Maps)

 

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By Cameron K – 2014-02-27

Episode 11 – Plant Materials

image of plant wire test setup

Image of plant wires ( source)

This week on LASER we have a plant materials themed episode where we discuss cellulose nanocrystals for use in composites, using plants as wires for computing, and using green tea to synthesize gold nano-stars for cancer treatments, drug delivery, and photonics.

2:00 Introductions and Emily explains the shiny new lab she is working for!

4:30 we start in on “The Elastic Properties of nano-crystalline cellulose”  calculated from first principals. (Article and PAPER)

6:20 the calculations from this paper come from Density Functional Theory, a complicated, but fairly accurate method of simulating material properties.

13:00 one good application for cellulose nanocrystals is in short-fiber composites.

14:00 its not exactly like glass…

19:20 Alex has never listened to an episode of the podcast.

20:20  This paper (published on the arXiv) is called “Towards Plant Wires” from “The Unconventional Computing Centre” of “University of the West of England”

21:20 the only electrical measurements made on plants in the past were impedance measurements on cucumbers to measure their physiological state? This seems strange, let us know if you’ve found anything else.  ***We also found http://link.springer.com/article/10.1023/A:1004684310108 Measurement of the activation enthalpies of ionic conduction in apples” ***

22:20 they measured the electrical properties of 3-4 day old lettuce sprouts!

25:00 The resistances measured from these lettuce seedlings is in the Mega-Ohm range (1000000 Ohms), so the measurements suggest the plants are  insulators.

26:50 Cameron has some problems with the methods of making contact to the plant.

27:50 we mixed up the units, Distilled water is 0.2 MOhm-meters, while DI water is 15MOhm-cm, so the distilled water is really only 0.002MOhm-cm, much lower than the resistivity measured.

42:15 This paper (also from the arXiv) is titled “Green tea induced gold nanostar synthesis mediated by Ag(I) ions”
43:35  They use Green Tea to reduce Silver Nitrate which then helps the formation of gold nanostarts that nucleate on the Silver ion

47:00 Gold nanostars are useful for photonic applications (LEDs, photovoltaic/solar materials, like Quantum Dots), drug delivery (where we can put drugs on or inside the nanoparticle, then functionalize the material to only attach to certain cells, and then deliver drugs directly where we want to in the body), and cancer imaging (where cancer cells will uptake more nanoparticles and then they are easy to image using Near-Infrared radiation.

52:30 I asked @thecollapsedpsi on twitter, and @murphyslab responded to say that citrate is often used to reduce Au3+, so they think it is likely that green tea could be used.  Thanks for the quick answers!

54:20 what were their motivations for even trying green tea? they mention it is a “green” process and “non-toxic”  but we don’t really buy the non-toxic argument without more analysis.

58:00 Thanks to Alfonso for leaving us a rating on iTunes and a comment on the website!

Instead of being topically relevant, the music this week are songs we mentioned/sung during the recording.
Intro:  Open – Crying (Get Olde)
Intermission – Monty Python’s Holy Grail
Super Rad – The Aquabats!
Outro:  Dreams are Maps – The Wild (Dreams are Maps)

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By Cameron K – 2014-02-12

Episode 10 – Perovskites, Gold, and 3-D Metal Printing

This week on LASER we discuss Perovskite solar cells with organic charge transport layers, the horrible health effects of illegal backyard gold ore refining in Indonesia, and a new free open source metal 3-d printer from Michigan Tech. This show is also the first one we ever recorded entirely over the internet.

 

1:30 introductions for our first online-only show! (we’ve always done them at least partially in person before.)

3:00 Perovskite Solar Cells Employing Organic Charge Transport Layers. published in Nature Photonics http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2013.341.html

4:00 Perovskite solar cells are important because of their high carrier mobilities (the electrons and holes can more more easily)  This is pretty tough to describe in podcast, but Chris gives it a try. A few leading questions help out.

7:00 we want organic solar cells because they can be wavelength tuned and still be transparent, so your windows could turn IR or UV light into energy, while letting visible light pass through.

9:40 we discuss Multi-junction solar cells that are used to overcome the shockley-queisser limit that defines “maximum” solar cell efficiency (~33% for Silicon) https://en.wikipedia.org/wiki/Shockley-Queisser_limit

13:15 Chris’s research is into making a better buffer layer for organic charge transport layers. We trick him into explaining this.

14:45 When are we going to record that special episode explaining photovoltaics? it should be soon…

21:00 after an awkward transition, we end up in Indonesia, discussion small scale (backyard) gold ore refining, and its horrible environmental impacts. From THIS NY Times article http://www.nytimes.com/2014/01/03/business/international/small-scale-gold-mining-pollutes-indonesian-lands.html?partner=rss&emc=rss&_r=1

22:20 we explain the scheme for Mercury amalgam gold ore refining (which was a process used for a few hundred years–we didn’t find a source for the origin)

24:30 Mercury toxin is where the phrase “mad as a hatter” comes from. It also kills people by affecting your CNS, and causes serious birth defects and infertility.

31:00 Chase explains the modern process for Gold cyanidization process.  This is a common modern practice for gold ore refinement, started in 1887, and has caused a lot of environmental contamination around California, where it was used following the gold rush. Even with cyanide, it is considered safer than the mercury process.

33:00 we really should have studied our chemistry before describing the process… sorry!

36:30 chase gets indignant about “who needs gold other than scientists?!”

37:00 we should add that “78% of the gold consumed each year is used in the manufacture of jewelry.” (via http://geology.com/minerals/gold/uses-of-gold.shtml)

38:40 Chris didn’t talk much during this because of he was so emotional for the plight of the Indonesians exposed to the mercury.

40:00 Metal 3-d printing!  This paper is open source, so its free to read, and it describes how to build their printer! https://www.academia.edu/5327317/A_Low-Cost_Open-Source_Metal_3-D_Printer  10.1109/ACCESS.2013.2293018

41:50 based on the open source reprap 3-d printers  (http://www.reprap.org/wiki/RepRap).

43:00 the deposition used is a gas metal arc welder instead of the usual stock extrusion tube.

45:47 the inside areas of the part were much softer than the outside because of the additive manufacturing technique.

49:30 the 3-D printed GUN controversy! (these still wouldn’t hold up to repeated use, so not more useful than a homemade pipe gun)

52:45 we wrap up the metal 3-d printer and our plans for how to use these in the future, and apparently Chris would 3-d print a  counterfeit car.

55:00 we’ve joined the AMAZON ASSOCIATE PROGRAM  so before you buy anything on amazon, please use our referral link; it won’t change the purchase price, but we’ll get a small portion back.

After the show we talk for a little while about Soylent  and its advantages for people working in the lab (How great would it be to be able to work in the lab all the time and not need a lunch break!)

and if you want to offer chase a job, email us a [email protected]!

Song 1: walkin’ on sunshine
Song 2: burl Ives silver & gold

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By Cameron K – 2014-02-01

Short Update & Help LASER!

Just a quick update about our plans for the future, and some begging for ratings and reviews, topic suggestions, and interviews.

Now that we’re 10 episodes deep, and finally getting the hang of this podcasting thing, its time to start trying to expand our listener base, and make a couple changes to the show. We’re going to start recording short pieces trying to explain specific topics or experimental techniques in materials science & engineering.  We would also like to start inviting people involved in interesting things onto the show, and discussing with them.

So please help us out by leaving a rating and review, telling people about us, and if you are doing something interesting or know somebody else who is, please email us at cameron-at-lsaerpodcast-dot-com! Do the same if you have any STEM topic you want us to discuss.

Thanks,
Cameron

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By Cameron K – 2014-01-24