Welcome to STEMology – Show Notes

Season 1, Episode 3

Farting cows, birds breathing circularly, bio-ink, Hummingbird wings and DIY desalination

In this episode Dr Sophie Calabretto and Dr David Farmer talk about… the work being done to bring an end to farting cows, how bird’s ability to perform circular breathing could be the reason why they can fly, bio-ink is making incredible advancements in printing replacement parts, how one man’s love of hummingbirds is revolutionising the sounds in our society and a DIY desalination plant that could mean the end of water stress globally and rival solar panels for space on our rooftops.

Farting cows

So we’re going to make lots of seaweed and put it in the cow feed and that’s going to reduce the methane output, but it’s also going  to take  carbon dioxide out of the air. And that’s good.

Birds breathing circularly

Birds can breathe circularly and should therefore be excellent at playing instruments like the didgeridoo.


Lungs for everyone!

Hummingbird wings

We make a lot of noise and it disturbs animals, et cetera. And so part of it is actually just finding where the source is.

DIY desalination

They’ve basically created what I would like to call the love child of desalination and water purification or water recycling.


This is a “kind of, sort of, vaguely close” copy of the words that David & Sophie speak in this episode.

IT IS NOT 100% accurate.  We are very sorry if we have spelt something completely incorrectly.  If it means a lot to you to have it corrected, email us at stemology@ramaley.media

STEMology s1e3


[00:00:00] Sophie: [00:00:00] Welcome to episode three of STEMology, a podcast that is your one-stop podcast shop for the interesting, fun, and sometimes just patently bizarre news in science, technology, engineering, or maths.

[00:00:11]  David: [00:00:12] Your hosts are Dr. David Farmer and Dr. Sophie Calabretto.

[00:00:16]Sophie: [00:00:16] On today’s episode, we’re talking farting cows, birds breathing circularly

[00:00:21]David: [00:00:21] Printing lungs with bio ink, why hummingbird’s hum and DIY desalination.

Farting cows

[00:00:27]Welcome to today’s show. And today we’re going to start in the only way I can think appropriate to start, which is with the methane production by farting cows being reduced by seaweed supplement in their feed. Sophie thoughts.

[00:00:41] Sophie: [00:00:41] Oh, look, it sounds lovely. And to be honest, I actually really enjoyed reading this piece. I enjoy reading most pieces, but this was yes. Specifically about how we can make the farts of cows less offensive while  still keeping cows very, very juicy and delicious.

[00:00:55] David: [00:00:55] I don’t know if the offensive nature you say offensive, but do you mean like the me thing, quantities being dropped, but does that

[00:01:02] Sophie: [00:01:02] Yeah, offense less offensive for the atmosphere, dave. I’m talking on the atmospheres behalf.

[00:01:08] David: [00:01:08] Okay. Yeah, yeah. Offensive to the atmosphere. Now I’m on board, not offensive to the nose of the person

[00:01:12] Sophie: [00:01:12] No still. I still think it’s very much methane. Yeah. So apparently what they did was they took 21 Angus Hereford beef Bullock. So I don’t know if this is all encompassing for all beef bullocks and for 21 weeks they fed them. So they usual diet of hay, grains and corn, but they also supplemented . This with either zero low or high concentrations of red seaweed.

[00:01:35] David: [00:01:35] right. That’s right. And, it actually, it works really appealingly because for the stepwise increase in supplementation of the seaweed, they got a step rise decrease in the level of methane, which is very appealing and like establishing what scientists call causality, which is where we say this thing causes this change.

[00:01:52] Sophie: [00:01:52] yeah, exactly direct causality. And, I think I quite like this just because, so we eat this seaweed anyway. Did you know that I did re I did a lot of research on seaweed this week. And so this particular seaweed is also known as the red sea plume or limo coho in Hawaiian, which means pleasing or Supreme seaweed.

[00:02:10] And apparently it features a lot in poke balls. that’s hard to say, as opposed to like a ProCare ball, which is the prison that a Pokemon lives in a Poke

[00:02:20] David: [00:02:20] So it’s not a Pokemon prison, which is what I thought you were talking about. So what is the first thing you said?

[00:02:24] Sophie: [00:02:24] A pokey bowl. Have you heard this? It’s like it’s a food that is usually it’d be rice and vegetables and usually some kind of raw fish. And it’s a Hawaiian dish. There’s lots of restaurants here that just do poker balls. It might be a Sydney thing. Uh, but apparently the seaweed has a bitter taste that’s  somewhat reminiscent of iodine, which is slightly disturbing.

[00:02:44]So what they found though, so when they fed them more seaweed, They produced less meat thing while still, I think they consumed less food, but still maintain normal growth rates as well. So they had to eat less when they ate this seaweed, they produced less may methane. And the bit that I also really enjoyed, I got into a little bit of a.

[00:03:04]I guess I don’t want to say a Whirlpool in the internet to do with like beef grading, but so they got some professional beef graders, and consumer testing and grading revealed that there was no effect on the quality of the flavor of the meat and the marbling score range from 410 to 810, while all carcasses, regardless of treatment graded as either choice or prime, and those are the best kinds of grading I learnt. I ended up in a Whirlpool via USDA beef standard charts.  So it means that in fact, they eat less, they produce less methane, which is better for the environment. They’re still delicious, if not excellent. And I’ve actually heard other stuff about how good seaweed is.

[00:03:45] So I saw a documentary. It was a few years ago, it’s called 2040. And apparently they are looking at seaweed permaculture as a solution to help draw carbon down from the atmosphere. So we know that we need to reduce carbon emissions.

[00:03:59] David: [00:03:59] So we’re going to make lots of seaweed and put it in the cow feed and that’s going to reduce the methane output, but it’s also going  to take  carbon dioxide out of the air. And that’s good. Anyway.

[00:04:07] Sophie: [00:04:07] Yeah. So, I mean, they did it with kelp, but apparently all seaweed draws down carbon dioxide. So as you said, you’re actively sequestering carbon from the atmosphere while also reducing the amount of methane thing that a cow produces. And then all of this seaweed that you’ve used to sequester this carbon dioxide, we can actually use it.

[00:04:24] So obviously we’ve said that the cows can eat,  we can eat seaweed too. You can use it in fertilizers, biofuels, plastics, clothing. So I think what we’ve really established is we should only grow seaweed and everything should be made from seaweed from now on

[00:04:36] David: [00:04:36] And also, I don’t know if this is something that concerns you, but if you look in the paper, while the amount of methane produced goes down when they add the seaweed, the amount of hydrogen that they produce in the farts goes up.  Which is obviously the seaweed is like removing the methane.

[00:04:52] It’s breaking it down into carbon and hydrogen it’s released as hydrogen, which is good because if anyone listening like me was worried about the flammability of these cows farts, they are still highly flammable, which was a relief to me. I had a billboard sign halfway drawn until I made this realization, but it’s okay.

[00:05:10] And also finally, I read the inclusion of the seaweed actually seemed to reduce the cost of the food because it’s really cheap.

[00:05:16]Sophie: [00:05:16] yeah, just grow it in the ocean.

[00:05:18]So there you go. Seaweed, cow farts, winning combination, I think right now.

[00:05:23] So we’ve learned

Birds can fly

[00:05:31] so Dave now moving from our air leaving cows to entering birds. Um, I’m sorry. I’m really, I’m really pleased with that segue.

[00:05:43]So what we have found out recently is, so this is what that was done by New York university and the New Jersey Institute of technology, and they found that birds are far more efficient breathers than humans are due to their looped airways.

[00:05:58] So they had these strange looped airways and what that actually does it facilitates flow to go in one direction. So, you know, we have these lungs that are sort of these tree-like structures and the direction of the air oscillates as we inhale and exhale,

[00:06:10] David: [00:06:10] Yeah. Your diaphragm goes down and it pulls the air in like a backwards balloon and fills up all the alveoli and then everything recoils elastically, and the air comes out and you repeat the process and that’s breathing and that’s lovely because you don’t die unless you stopped doing it for like five minutes.

[00:06:25] Sophie: [00:06:25] And then your body will try to get you to do it again.

[00:06:28] David: [00:06:28] Well, no, if, if you’ve spend five minutes, that’s bad

[00:06:31] Sophie: [00:06:31] Oh, it’s too. It’s too late.

[00:06:31] David: [00:06:31] That’s very bad news. ,

[00:06:32] Sophie: [00:06:32] so birds, on the other hand actually have stationary lungs. Right. So they don’t breathe in and out, but they contain these looped airways. And as I said, they constructed in such a way that it leads to air flowing in one direction. So essentially they can inhale while they’re exhaling because this air is only moving in one direction.

[00:06:49] David: [00:06:49] right. So it seems like their lungs are actually, instead of this tree-like structure, their lungs are actually more like our vascular system, so that this is the system of blood vessels where you have the heart pumping the blood only one way and it comes back to the heart and then leaves again.

[00:07:02]That’s basically what they’re doing is they’re breathing in only one direction.

[00:07:05]Sophie: [00:07:05] And so I think we’ve known this for a long time. Right. But the difference is now they’ve sort of tried to work out the mechanism as to what makes this happen. And I got really excited because this is just fluid mechanics.

[00:07:16] So I read this paper. It’s my thing. And not only these, in my thing, the way that they tackle this problem at two things I actually surprisingly know quite a bit about.

[00:07:25] So yeah, they split it into two different things. They did some experimental work and some computational work. So the experimental work, they basically created a simplified rig. So simplified version of the bird lung made of tubes. And then what they did was something that we call PIV, which is stands for Particle Image Velasymmetry.

[00:07:44] So, what we do is in our fluid, we put tiny little shiny particles that will pearlescent

[00:07:48] David: [00:07:48] Those are the particles in the PIV.

[00:07:50] Sophie: [00:07:50] Yeah. They’re P they put They’re P in the PIV. And what you have is you got your fluid flowing, and then you have a very high powered laser sheet. So it looks like a very, very thin piece of laser paper.

[00:08:02] And you shine that at your rig in whatever orientation you want. Cause that’s going to pick up the plane that you’re looking in. So you can look at any cross-section

[00:08:10] David: [00:08:10] So that’s your imaging. So that’s the I and the PIV.

[00:08:14] Sophie: [00:08:14] That’s the I in the PIV. And then what you do is you sync that laser sheet with a super-fast camera.

[00:08:19] So every time you flash the laser, you take a picture and then you do that really quickly in succession, you go, then you take an algorithm that can stitch those individual images together, and you can actually track individual particles or all of the individual particles during this fluid flow.

[00:08:37] So you can actually quantify exactly what’s happening rather than just looking at the fluid flow in a qualitative way.

[00:08:44] David: [00:08:44] The particles are super shiny. the imaging involves a high powered laser and the V the velocimetry involves a super high speed camera. So does any part of this process not involve some kind of hair hyperbolic? Word added to the star of it. Super fast camera, high powered lasers, super shiny particles PIV.

[00:09:06] Sophie: [00:09:06] no, we really like to big ourselves up in experimental fluid dynamics Dave.

[00:09:12] Because it’s all very exciting. Yeah. So they did that. And then in combination with that, they did some computation. So they used a finite element method, which I won’t go into, but it’s a very standard way to compute things.

[00:09:22] When you’re looking at fluid flow, there are a couple of things that made me a little bit worried. So for starters, they used a package called Comso. I’m not going to go into Comso

[00:09:30] David: [00:09:30] But it you sad and short.

[00:09:32] Sophie: [00:09:32] It makes me a little bit sad and they solved the two dimensional Naveah Stokes equation. So the Naveah Stokes equations are the equations that govern all fluid motion.

[00:09:39] So that’s very appropriate here because we have fluid motion. We’re looking in two dimensions for the computations because they’re just a bit easier to do. So rather than doing the whole 3d geometry, you just looking at a cross section of the geometry. But they solved them for incompressible flow. And this is the bit that makes me a little bit uncomfortable because.. .

[00:09:57] So air is a gas and gas is compressible. An incompressible fluid would be a liquid fluid and the physics is quite different. Although the computations are much easier. If you do something on an incompressible flow,

[00:10:09] then a compressible flow.

[00:10:10] David: [00:10:10] on that note, presumably did the thing that they built, that the series of pipes that, where the pipes able to expand, because presumably the airways of a bird would also be able to expand to accommodate the flow of air.

[00:10:22] Sophie: [00:10:22] I believe the pipes were rigid.

[00:10:24] David: [00:10:24] Okay. So there’s a couple of things.

[00:10:26] Sophie: [00:10:26] There are a couple of things, but I guess overall what they wanted to do was just understand the mechanism or see if they could understand the mechanism and what they actually found was pretty cool. And so at one of the junctions in the middle of their little pipe rig, they found that they got flow separation and vortex shedding.

[00:10:40] So that just means that the flow has removed itself from the ball. And it’s created a little spinny disc of fluid. And that little vortex actually acts as a valve that opens and closes, which then closes off one direction to the other. So they’ve created a little fluid valve

[00:10:58]out of spinning

[00:10:59] David: [00:10:59] basically. They’ve made a little machine just using a particular flow of fluid. I’m not being very eloquent right now because I have no idea what’s going on, but I’m having a fun time.

[00:11:09]Sophie: [00:11:09] so yeah, so basically the fluid, what happens with the way that the fluid moves in this geometry, you end up getting a vortex and that vortex is in a position that acts like a plug. And that plug means that the fluid can’t actually go through that junction, it can only go in one direction.

[00:11:23] David: [00:11:23] That’s amazing. See, you don’t even need a biological structure to accomplish this function. It just happens because the fluid does it.

[00:11:29] Sophie: [00:11:29] Yeah. And this actually has amazing applications because directing, controlling and pumping fluids is super important in a bunch of applications. So you’ve got, I don’t know, chemical processing healthcare, you’ve got machinery. You need to control the way… I don’t know, coolant and lubricant and fuel and stuff moves.

[00:11:46] So actually being able to control the direction that fluid moves just using a particular geometry is actually pretty spectacular. And it also means that birds are just better breathers than osteo and they do it.  They evolved with this knowledge in a way that we are just learning

[00:12:02] David: [00:12:02] So birds can breathe circularly and should therefore be excellent at playing instruments like the didgeridoo. And should they ever be lucky enough to acquire wings and hollow bones, didgeridoo players by that logic ought to be really good at flying.

[00:12:13] Sophie: [00:12:13] Fine. Yeah. Correct. From my understanding.



[00:12:20]David: [00:12:20] So as guilty as I feel about using the letter B as a segue from birds to bio-ink

[00:12:27] Sophie: [00:12:27] no, it’s perfect. It’s perfect, too perfect. Tell me about, tell me about bio-ink Dave.

[00:12:32] David: [00:12:32] So this is some work by some scientists in Sweden, at the loon university. And what they’ve managed to do is design a bio ink, which enables small human sized airways, which is the bit what your wind pipe branches into to be 3d bioprinted with the help of patient STEM cells for the, what they say is the first time.

[00:12:53]Sophie: [00:12:53] so that’s fairly amazing.

[00:12:55] David: [00:12:55] Yes, it sounds amazing. Doesn’t it? So a bio-ink is my understanding of a bio-ink is a material that’s used to produce engineered or artificial live tissue using 3d printing. So basically it’s something that you can put into a 3d printer, some kind of material, some kind of viscous material, but you’ve embedded it with STEM cells of some kind.

[00:13:13] And then you can print them in a shape that you like, like a 3d printer would do. And then hopefully a combination of the shape that you make and the cells that you choose lead it to producing a structure, which fulfills a particular function and this case, an airway.

[00:13:30]Sophie: [00:13:30] I mean, that’s crazy. Impressive. So we can 3d print in so many things now we can essentially 3d print in flesh.

[00:13:39] David: [00:13:39] Yes, we are printing flesh bits of people. So what was the really cool bit of this? There were two really cool bits of this, I think. The first really cool bet was that they printed, they managed to, they basically made a medium, they made a new medium, which I wondered if you might be excited about Sophie because there was fluid dynamics and sheer and all these exciting things.

[00:13:57] These exciting

[00:13:58] Sophie: [00:13:58] uh, Dave, you saw the word shear. I really just, you know, at the end, I just want to talk about sheer thinning fluids for just a second, but

[00:14:04] David: [00:14:04] I didn’t, I didn’t just see the word shear. I saw the word shear and thought for you.

[00:14:09] Sophie: [00:14:09] You spoil me.

[00:14:11] David: [00:14:11] So,  they basically made a new, like kind of matrix or whatever it’s called to am 3d print and then embedded it with STEM cells. And then what they did was they took two to three different kinds of cells and endothelial layer, and then two smooth muscle cell layers, which is what you find in human type airways and 3d printed them into a tube shape, which had a diameter of less than four millimeters and showed that in a mouse model of immunocompromised patients, which is basically if people receive a transplant, like if there’s something wrong with their lungs and they need a lung transplant.

[00:14:43] Then they take immunosuppressive drugs. So they tolerate the transplant. So they had these mice that were immunosuppressed and they implanted these 3d printed airways under the skin of the mice and found that they were tolerated in that the mice dealt with it. And that, that was fine. So these were basically suitable for transplantation.

[00:14:59] If only we could make them quite a bit smaller.

[00:15:02] Sophie: [00:15:02] right. And yet I also read that, when they transplanted them under the mice skin, they also supported new blood vessels.

[00:15:09] David: [00:15:09] right. So this was the other really cool bit. So all they had to do was make the airways. So the whole point of the lung is to take air and bring it into really close contact with blood so that the oxygen moves into the blood and the carbon dioxide moves out, and you breathe. And that’s what breathing is we have already talked about today conveniently.

[00:15:26]What they showed was all they had to do was make the airway and then implant it and then the material that they use to 3d print actually facilitated blood vessels, moving in from the host organism into the area that had been transplanted.

[00:15:40] So they reckon if you could transplant this into a person, that person would develop their own vasculature, which is less complicated than building it for them. And that, that would enable them to have a transplanted lung tissue that’s been 3d printed.

[00:15:52]Sophie: [00:15:52] which is amazing. So do we just need to try this out on larger animals? Make sure it works. And then, uh, lungs for everyone.

[00:15:58] David: [00:15:58] lungs for everyone. So they say the limitation is not a biological thing. The limitation is the resolution with which we can actually 3d print things. So we just need exquisitely, exquisitely, tiny nozzles in order to make tiny, tiny, tiny, tiny air SACS at the, at the bottom. If you’re long and not just make one or two of them, you need to make like billions of these things, depending on the size of the thing.

[00:16:21]Sophie: [00:16:21] so funnily enough, they actually had a similar problem, 3d printing metal in Darwin, the size of their nossel, they couldn’t make it small enough. It’s a, it’s a real thing.

[00:16:30] David: [00:16:30] and the in printing what?

[00:16:31] Sophie: [00:16:31] Sorry. So when they’re in Darwin, they were trying to 3d print metal. And they managed to do that, but they could only make sort of course things I say die.

[00:16:39] I’m just not referring to the particular company. Uh, but it’s but yeah, so they have managed to 3d print metal and they could print these out very, very quickly. These large pieces. Of, you know, stuff that you could stick into machinery if something broke. So it was like very quick. So rather than having to actually cast metal, which takes an insane amount of time, you can just 3d print this thing.

[00:16:59] And they found that their limitation as well was the size and the nozzle. They couldn’t get anything small enough. And when they got it too small, what they actually did is they disrupted a turbulent boundary layer in their nozzle. And they couldn’t control the stream and it got a little bit crazy.

[00:17:11] David: [00:17:11] And is that, is that where shear comes into it? Sophie

[00:17:14] Sophie: [00:17:14] What not even shears is.. I just got really good excited when I saw that it was sheer thinning. So have you heard of sheer thinning fluid very quickly, Dave? So she had thinning fluid is just a fluid that basically, the viscosity reduces when you apply a sheer strain. So a good example of this is toothpaste.

[00:17:31] So if you think about toothpaste, you take the top off the toothpaste and if you hold it from the end, so the top is pointing down. All the toothpaste stays inside. Right? It’s a fluid, but it stays inside. But then when you squeeze it and you apply that sheer strain, it flows. So the viscosity reduces and flows out of your toothpaste tube onto your toothbrush.

[00:17:52] That’s sheer thinning. And then you’ve got like shear thickening fluids, which is, I don’t know if you’ve heard of Oobleck

[00:17:56]David: [00:17:56] Yeah. So  would these be examples, different examples of non-Newtonian fluids.

[00:18:00] Sophie: [00:18:00] Yeah, exactly. The thing is I think shear  thickening is slightly more common. So yeah, with Oobleck, if you put your hand in, if you gentle, it’s

[00:18:07] David: [00:18:07] and for the audience that’s as opposed to Newtonian fluids like water, right. Which behave in a, in a Newtonian normal way

[00:18:14] Sophie: [00:18:14] Essentially they’ve this viscosity doesn’t change. Their viscosity, so that the runniness of the fluid stays fairly uniform.

[00:18:21] Whereas you’ve got these special fluids where if you do something to it, the runniness of it changes. And so I think it’s just really interesting that this bio-ink is a little bit like toothpaste in some ways, but in really only one way in a very limited way.

[00:18:34] David: [00:18:34] You mentioned Darwin. So I just want to say as a fan of both intricately made tiny 3d printed metal things and of new lungs for everybody. What are you doing 3d print manufacturers? Like get off your arses and make higher resolution ones so that we can get on with it.

[00:18:52] Sophie: [00:18:52] We can have lungs and tiny metal parts.

[00:18:54] David: [00:18:54] go. That’s all we

[00:18:55] Sophie: [00:18:55] you

Hummingbird hum

[00:19:05] all right, David really want to talk about birds again?

[00:19:08] David: [00:19:08] Well, we can,

[00:19:09]Sophie: [00:19:09] Well, good, because. There was some work that was done as it was joint work from  Stanford and the Eindhoven university of technology. And basically they want to know what makes a hummingbird hum.

[00:19:22] David: [00:19:22] Wait, so hummingbird’s hum. And that’s why it’s not just a clever name.

[00:19:26] Sophie: [00:19:26] no they’re called hummingbirds because of  the humming sound they make when they fly. But you

[00:19:31] David: [00:19:31] I’ve never seen nor haired one in real life. So I

[00:19:33] Sophie: [00:19:33] really. I mean, I, I say that I don’t think I have either. I’ve seen them on the internet or television or something. So, but I know, you know, they made this little humming sound a bit, you know, like a mosquito that makes a bit of a buzzing sound.

[00:19:44]There are a lot of animals that when they flap their wings very, very fast that they make a certain sound and a hummingbird makes a hum.

[00:19:50] David: [00:19:50] Yes. So this team of scientists were interested in exactly why the hummingbird hummed, as opposed to, they mentioned some other animals, mosquitoes wine, bees buzz, hummingbirds hum, and larger birds whoosh.

[00:20:03] Sophie: [00:20:03] whoosh. I liked that

[00:20:06] David: [00:20:06] Turns out that the answer is in all to do with how the hummingbird flaps its wings. Now the wish sign with the birds is a, is a good one to talk about for a second, because if you’ve seen a bird fly, it flaps his wings down, and then it kind of folds his wings in and puts them up again and then spreads them out and then put them down.

[00:20:23] So if you hear the birds, wings go, it’s when it’s flapping down and it makes it kind of whoosh sound or a flapping sound, if you will. And that’s because they’re generating all of the lifts for flight on the downward flap, not the upward, the upwards, just putting the wings out of the way more than anything.

[00:20:38] And the downward is just the flap, the up, whereas hummingbirds are completely different. Hummingbirds somehow in a way that I don’t fully understand, managed to generate lift both when the wing is going up and when the wing is coming down. And apparently when they put the wing up very quickly in succession. That is what the humming sound is.

[00:20:58] Sophie: [00:20:58] Yeah. And so I looked at the force diagram they had in this paper and it was just a little bit too much for me. I think emotionally and mentally, but so I did look into hummingbird flight a little bit and basically their wings work a little bit like aerofoils so it comes down to Bernoulli’s principle.

[00:21:15] So just means that because of the sh of course it does because of the shape of the hummingbird wing, the air flows faster across the top than it does underneath. And fast flowing air means lower air pressure. And then the slower flowing air is higher air pressure, but the high air pressure is underneath the wing.

[00:21:33] And so you’ve got this high pressure underneath and there’s low pressure above the wing. And that causes basically the lift. It creates the lift under these wings that sort of how an air foil works. And that is maybe a bit of an explanation as to how they still generate upward force when they moved their wings both up and down, it’s just the shape of the wing.

[00:21:53] David: [00:21:53] Okay, that makes sense. Cause it has to be something.

[00:21:56] Sophie: [00:21:56] it has to be something, that was the only thing on the internet that I could find that was peer reviewed.

[00:22:00] David: [00:22:00] So what I loved about, so did you read about how they did this? So they used 12 high-speed cameras, six pressure plates and 2,176 microphones. And I think that’s per bird.

[00:22:13] Sophie: [00:22:13] yeah.

[00:22:14] David: [00:22:14] So they had to, my understanding of this is that they built up a 3d model of where the center. So they listened with these, that many microphones to where the sound was coming from.

[00:22:23] And then they had the high speed cameras, so they used all of those microphones to build up a 3d image of the sound around the bird. They then had to synchronize that with the camera because it’s all out of sync because obviously the light is reaching the camera much more quickly than the sound is hitting the microphone.

[00:22:39] So they had to. Sync that up in order to figure out what was going on. And it just seems like just a staggering amount of work.

[00:22:48]Sophie: [00:22:48] It’s the sound equivalent of a heat map. Essentially. They have all this data and then they use AI to determine the most probable sound field of a hummingbird. So they did all of that. Then they had too much data. Then they use artificial intelligence to determine this kind of model for the most probable sound field of a hummingbird.

[00:23:07]David: [00:23:07] Okay. So why, why have they done this?   Well, there’s some things I like about this. So first they speculate that this could be really useful for making things like drones and fans, more quietly in industrial settings. but the guy clearly just, what are these guys really just clearly loves what they’re doing, because what they say is the, here’s a quote, here’s a quote from Dr. Latinx.

[00:23:27] Sophie: [00:23:27] I think I may have written down the same quote as you, but I’d like you to read it.

[00:23:30] David: [00:23:30] Okay. Dr. David  of Stanford university says ” the distinctive sign of the hummingbird is perceived as pleasant because of the many overtones created by the varying aerodynamic forces on the wing. A hummingbird is similar to that of a beautifully tuned instrument.” Latinx explains with a smile. It says, and I just. He clearly just

[00:23:50] Sophie: [00:23:50] I wrote down the same thing.

[00:23:52] David: [00:23:52] Clearly just loves hummingbirds. And I love that because this is applicable research, which has been done because someone just really wanted to know.

[00:24:00]Sophie: [00:24:00] but he does actually bring up an interesting point. And I know that there’s a reference back to these sound cameras. The connection of they’ve got the cameras, they’ve got the microphones, they’ve got all this set up, they’ve called it sound cameras. And they’ve said that generally we do need to eliminate a lot of noise that we create because you know, we’ve talked about this before.

[00:24:15] We make a lot of noise and it disturbs animals, et cetera. And so part of it is actually just finding where the source is. Cause if you don’t know where the source of the sound is, you can’t eliminate the sound. So this is a step towards accurately modeling the starting point of sound in a lot of different applications.

[00:24:31] So that then we can get rid of that sound. So

[00:24:33] David: [00:24:33] yeah. Forget wings. Anything that makes us sound, then you don’t understand how the sound is made. This provides a means of understanding how the sound is made, and if it’s ugly, you can then work to stop it.

[00:24:42] Sophie: [00:24:42] yeah, that is the claim.

DIY Desalination

[00:24:47]David: [00:24:47] So I’ve never seen a hummingbird in real life but I associate them with kind of idyllic settings. And do you know what else is kind of idyllic?… Not being thirsty.

[00:25:00] Sophie: [00:25:00] That you know what Dave, that is correct.

[00:25:02] David: [00:25:02] Not being thirsty in my ideal universe. I am not thirsty.

[00:25:06]Sophie: [00:25:06] In everyone’s ideal universe they’re not thirsty and there’s been some work that’s come out of  Edith Cowan university from the school of engineering. And they’ve basically created what I would like to call the love child of desalination and water purification or water recycling. And they’ve created these mini desalination systems that are powered by the sun and this small enough to fit on a residential rooftop. And they’ve included right next to you solar panels, because we are all interested in the environment.

[00:25:34] David: [00:25:34] So basically they’re envisaging a situation where maybe there’s going to be some climate change and there’s going to be a bit of water pressure, cause there’s going to be less rain. So basically you’re not going to rely exclusively on the water company for providing your water or you are. But once you’ve used some of that water, like say for showering, et cetera, that gray water, you can then use it.

[00:25:53] It can go into the system, which is powered by the sun, which you obviously had your solar panels to power and it’s going to clean the gray water for you. And then you’re going to have a local source of purified recycled water.

[00:26:04]Sophie: [00:26:04] Yeah, exactly. So it only works with gray water. You can’t use it for sort of, you know, Blackwater or the nasty waters, but basically what they’ve done it’s put yet it’s proved by, we can say poop. We’ve talked about poop canons and torpedoes and things before. So what they did, at this stage, there are sort of two different ways to purify water.

[00:26:21] So there are the membrane- based methods where you basically force fluid through a permeable membrane and you leave all the crud on one side and all the good water on the

[00:26:30] David: [00:26:30] other side

[00:26:30] So that’s like, that’s like making coffee,

[00:26:32] Sophie: [00:26:32] Yeah. It’s making exactly it’s making coffee. Yeah. So it’s getting the little particles of actual ground coffee out of your delicious cup of coffee.

[00:26:39] So that’s exactly that. And then the other ones are a little bit like distillation, right? So we’re using heat energy to turn water into vapor. And then basically you collect the water vapor and then when you call it down, it turns into, you know, pure water. Cause you’ve left all the crud because crud doesn’t evaporate

[00:26:55] David: [00:26:55] Right. So distillation, I’m more familiar with, cause obviously it’s something that the Scottish people are very familiar with. Well, they make whiskey, they don’t make water because there’s an abundance of that falling out of the sky in Scotland, but distillation. Absolutely.

[00:27:06] Sophie: [00:27:06] Dino. You’re very lucky with you rainfall and you shouldn’t show off Dave. And so, uh, so what they’ve

[00:27:11] David: [00:27:11] Yeah. I shouldn’t have immigrated to avoid it. Either of these guys are right.

[00:27:14] Sophie: [00:27:14] yeah, exactly. Go back and take me with you. No, so what they’ve done is they have created. It’s basically both of these things. So they use hot water from the sun. So they’re using hot water from the sun to actually turn the water into steam. So they heat pipes, it turns the water into steam.

[00:27:32] This steam is then pushed through a membrane because the steam will travel through the membrane more easily than trying to push water through a permeable membrane. And on the other side, it’s cooled. And then you get nice drinking water.

[00:27:44] David: [00:27:44] Lovely. One of the things I really enjoyed about this story was the quotes from the people who did it. “simple engineering, the engineering challenges in creating a rooftop recycling system were minimal.”  and also “from an engineering side, we didn’t experience any real problems, it was relatively simple.” So just like, yeah, we just solving this problem. Yeah. It wasn’t even hard. What do you want to do now?

[00:28:05] Sophie: [00:28:05] Yeah. They’re like, we nailed it one to be honest. So I did a little bit of searching into desalination and drinking water. And apparently by 2025, 14% of the world’s population will be facing water scarcity, which is  pretty soon, and that’s a fairly big proportion of the population, but not including that 14%, two-thirds could be under what they call stress conditions, which means you’re not completely out of water, but you’re on the verge of starting to panic. So this is,

[00:28:31] David: [00:28:31] That’s that’s that’s, that’s borderline idyllic. Like the hummingbirds are still around, but they’re reduced in number and you’re quite thirsty, but you’re not completely out of water.

[00:28:40] Sophie: [00:28:40] Yeah, exactly. So if this means that this is very easy and cheap to make, everyone can stick one on their roof.  And there you go, we all have fresh drinking water.

[00:28:49] David: [00:28:49] cheers.


[00:28:50]  Sophie: [00:29:00] And thank you for listening to another fun episode of STEMology.

[00:29:04] Be sure to check out the links to all these great stories on our show notes. Go visit www.STEMology.com.au

[00:29:11]David: [00:29:11] if you have any news, you think is STEMology- worthy, drop us an email at STEMology@ramaley.media. We would love to give you a mention.

[00:29:19] Sophie: [00:29:19] Your hosts have been Dr. Sophie Calabretto and Dr. David Farmer.

[00:29:23]David: [00:29:23] This is a podcast from Ramaley Media.

[00:29:24] Our executive producer is Melanie De Gioia and Elizabeth Rose did the music.

[00:29:29] Sophie: [00:29:29] Be sure to hit subscribe on your favorite listening app, so you never miss our episodes.

[00:29:33]David: [00:29:33] We look forward to sharing the latest in all things, science, technology, engineering, and maths with you next week on be sure to bring your friends.