Chemistry World Podcast - July 2009
00:12- Introduction
02:01-- Finding the toxic species that seed Alzheimer's?
05:10-- Sugars to stop termites in their tracks
08:05-- Colin McInnes describes solar sailing
14:41 -- Super-light molecular sponges soak up hydrogen
16:44-- Nanotubes accelerate pollutant uptake by plants
20:53-- Chemistry in its Element - Erbium
27:03 -- Tracking down toxic mushrooms
29:05-- Salt crystals drawn into wires
32:23-- The chemical conundrum - what did British scientist William Bird Herapath discover in 1852 when he added tincture of iodine to the urine of dogs that had been fed quinine?
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
(00:12 -- Introduction)
Interviewer - Chris Smith
Hello! Welcome to the July edition of the Chemistry World podcast which is brought to you this month by James Mitchell Crow, Nina Notman and Matt Wilkinson. In this episode, you've heard of spaceships, well, in future, we've reason to think that they might really go sailing through space.
Interviewee - Colin McInnes
So, in practice you'd have an extremely large highly refractive, but very, very light weight mirror in space and as sunlight reflects off the sail, the photons bounce of the sail they impart a very small amount of momentum and the sail is giving us a tiny, tiny pressure about maybe one thousands of the feather gracing in the palm of your hand but that very small pressure is sufficient to accelerate the source over a period of days, weeks, months or years.
Interviewer - Chris Smith
That's Collin McInnes, he will be explaining just how those solar cells work and what sorts of machines might benefit from them, in just a moment. Also on the way, worrying news from the world of nanotubes, at least if you're a plant.
Interviewee - James Mitchell Crow
The carbon nanotubes are actually acting like tiny hypodermic needles and they were piercing the plant root cells and then effectively acting like a little tube through which other pollutants in the environment were very quickly then taken up inside the plant.
Interviewer - Chris Smith
And strange goings on in the salt cellar too.
Interviewee - Matt Wilkinson
Most of them would mention table salt to be a brittle crystalline material. If you have a salt crystal in front of you, you hit with a hammer and it snaps and you wouldn't expect it to be able to put it into nanowires, but that's exactly what makes the Nathan Moore and his team at Sandia National Laboratory in Albuquerque in New Mexico have found.
Interviewer - Chris Smith
So salty nanowires, seasoning perhaps for computer chips, who knows. Hello! I'm Chris Smith and this is the Chemistry World podcast.
(Promo)
The Chemistry World podcast is brought to you by the Royal Society of Chemistry. Look us up online at chemistryworld dot org
(End Promo)
(02:01 -- Finding the toxic species that seed Alzheimer's?)
Interviewer - Chris Smith
These days, thanks to better nutrition, sanitation and healthcare, we're all living a lot longer, but longevity is something of a mixed blessing because it increases the risk of developing Alzheimer's disease. This is caused by the build-up in the brain of a protein called beta amyloids, which kills nerve cells, but scientists have always struggled to explain exactly why this protein accumulates in the first place, but now James, some light seems to have been shed on this problem.
Interviewee -James Mitchell Crow
This is a team led by Michael Bowers at the University of California, Santa Barbara and they think using a new mass spect technique, they might have identified the primary toxic species behind the development of Alzheimer's disease and the formation of those big protein plaques that are associated with brains of Alzheimer's patients.
Interviewer - Chris Smith
Well, tell us a bit about those first. Actually, when you look in the brain of someone with Alzheimer's what do you see and what's going on?
Interviewee - James Mitchell Crow
Basically what do you see, are these long rigid rods of misfolded proteins, all clumped together. There's a couple of different forms of the amyloid beta protein depending on exactly how many amino acids there are in the chain, the 42 amino acid long beta protein is believed to be the most toxic. So, what they've done is compared how this forms the initial aggregates of the dimers and trimers against the 40 amino acid long peptide.
Interviewer - Chris Smith
So what you're saying is that cells makes this beta amyloid, there is a 42 amino acid form of this which in some ways self-assembles to makes these aggregates, which are toxic. There's also a short form, the 40, which is less toxic and this is kind of giving us some hints as to why we see that difference.
Interviewee - James Mitchell Crow
That's right; well that's what this team believe. So, as I say what they've done is compared how these initial aggregates form when they studied amyloid beta 42 they found that dimers formed, then they pair up to form tetramers and then another dimer joined into form hexamer and so till they formed a dedecamers, whereas amyloid beta 40 formed dimers and then tetramers, but then the process really stopped there. Form the tetramers to form the really long fibrosis in extremely slow process, whereas from the dedecamers to the fibrosis is slightly quicker, so why that's why they believe that the amyloid beta 42 might be the more toxic.
Interviewer - Chris Smith
Answering an important question, but of course another important question to actually ask is does this inform us of a way to interrupt the process or stop it so that people don't get Alzheimer's.
Interviewee - James Mitchell Crow
Well, they think that that actually might be the case. What they did was they used ion mobility studies and basically you can imagine this as separate molecules based on their shape and what they found is that amyloid beta 42 tetramer, the more toxic regime, had a quite open shape, so if you could somehow interrupt that initial aggregation process then they hope that that might be a way of treating and preventing the disease.
Interviewer - Chris Smith
Let's hope so, because we're getting older and we have an aging population in the UK, I think, something like one person in every five over the age of 75 gets Alzheimer's disease. So let's hope they solve that one before we get there. Thank you very much James.
(05:10 -- Sugars to stop termites in their tracks)
Interviewer - Chris Smith
Now, from a pest in the brain to a pest in the garden, especially if you live in Australia, Matt, some friends of mine said they cannot have a wooden fence in Australia; they have to have a metal one, because if they do have a wooden fence, the termites get in, now you might have the solution.
Interviewee - Matt Wilkinson
Well, it's not me that's got the solution, but some researchers from MIT and Northeastern University in Boston in the States have come up with a cheap environmentally-friendly way of killing termites. What they've done is they had a look at how termites fight off various fungi and they found that they recognized the fungi by the sugars that the fungi express on their surfaces and when the termites actually see these sugars, it elicits an immune response which allows the termites to kill them off and they stay healthy and they then tried to look at blocking these receptors so they could make the termites weaker.
Interviewer - Chris Smith
So, the termites have got some kind of chemical docking station or receptors that can spot something on the surface of the fungus and that's how they know the fungus is there or whatever they are reacting to and you're saying that now scientists are looking for chemicals or molecules that would pretend to be a fungus block up the molecule and meanwhile the fungus or some other pathogen can, sort of, slip under the radar.
Interviewee - Matt Wilkinson
Exactly, in fact they found that a certain sugar derivative known as d-delta-gluconolactone can actually block these receptors so that the termites can't elicit an immune response and they found that by adding these gluconolactone to termites in the presence of various fungi, the termites would die.
Interviewer - Chris Smith
How do they seek to use this and can you get gluconolactone onto the termites fairly easily, where does it come from?
Interviewee - Matt Wilkinson
The gluconolactone that they used, they actually made in laboratory and it's a relatively simple molecule with just a couple of chiral centres, it's is not too difficult to make, but its actually also naturally occurring and so they believe that while they could integrate these gluconolactone into nanoparticles, maybe paints, they also think that they could be produced genetically by engineering plants, so you could genetically engineer the plants that the termites eat and then they would seems to be killing themselves by eating them.
Interviewer - Chris Smith
Is it just termites, given that they are insects and there are many members of the insect world, will this also hit other insects or could that plant defense mechanism actually be a very good pesticide across the board?
Interviewee - Matt Wilkinson
It is quite widely applicable to quite a few different types of insects, not just cockroaches, but also locusts, which means that this gluconolactone might help in the pest control of up to three different insect groups, which could be a huge benefit and obviously this is all happening in an environmentally friendly way, which means that you don't have the problems associated with putting toxic chemicals into the environment to which the pests can actually become resistant to and they can also bio-accumulate and cause problems to us, when we eat products that they've accumulated in.
Interviewer - Chris Smith
Despite green immunosuppression, what a wonderful concept, thank you Matt.
(08:05 -- Colin McInnes describes solar sailing)
Interviewer - Chris Smith
Now from environmentally friendly insect control, to perhaps the greenest form of space travel and that's using the power of the sun itself, Colin McInnes.
Interviewee - Colin McInnes
The idea of solar sailing is that you take a very thin highly reflective membrane and you package it into the nose corner of a rocket, a conventional satellite launcher and then in space you have a mechanical device set of maybe telescoping booms, which through the sail film and keep it in tension. So in practice, you'd have an extremely large highly reflective, but very, very light weight mirror in space, perhaps 40 or 50 meters across and as sunlight reflects off the sail and the quantum packets of energy photons from which sunlight is composed of, the photons bounce off the sail they impart a very small amount of momentum to it and the sail is giving a tiny, tiny pressure, about maybe one-thousandth of the pressure of a feather gracing in the palm of your hand but that very small pressure is sufficient to accelerate the source very slowly over a period of days, weeks, months or years and achieve very large changes in the energy and that means that the solar sailing can be used for either very long duration or very high energy machines in the solar system.
Interviewer - Chris Smith
Wasn't the first person to suggest that this might be possible at least theoretically, someone about 3 or 4 hundred years ago; it was Kepler, wasn't it, from his observations on comet?
Interviewee - Colin McInnes
Yeah, Kepler noticed that comet tails always point away from the sun and his hypothesis was that there is something emanating from the sun, which pushed the comet tails away with light pressure and the dust coming off the comet, which is pushed away from the sun by the pressure of sunlight and with that seems physics which should be used to propel solar sails spacecraft through the solar system.
Interviewer - Chris Smith
What sorts of speeds do you think you could get to with this technology then?
Interviewee - Colin McInnes
Well, it depends on the machine application and depending on how you tilt the sail, how you orient the sail, oriented towards the sun, you can either gain or lose energy, so for example, you could spiral in close to the sun, you could perhaps do a mission to mercury, which is actually very, very difficult to get to using conventional chemical rockets because mercury zips around the sun once every 88 days compared to the earth takes you know 365 days around the sun or if you're to pass close to the sun, then the increased light pressure on the sail would accelerate the sail fairly quickly and you could zip over to the outer solar system. One of the missions, which we've investigated in the past for the European Space Agency is using a trajectory, which does a close fly-by of the sun to get to the distant outer solar system, called heliopause, the very, very edge of the sun's influence and gets sent to the edge of interstellar space and to get there at it takes about 25 years, which is a task almost impossible for conventional spacecraft, but would be achievable by solar sail space craft in the future.
Interviewer - Chris Smith
So practically speaking, how do you make this a reality?
Interviewee - Colin McInnes
Well, that's the question -- there has been a number of studies done over the years and we've been doing work for the European Space Agency, we've been evaluating different mission concepts, there has also been ground tests of solar sails with 20 x 20 meter sails which have been deployed in ground both in Europe and in the US and really the technology is no where and a state change is required to go from a ground test and paper studies to actual flight demonstration.
Interviewer - Chris Smith
But there is no one actually tried testing the phenomenon or at least got something into space to prove that this can work?
Interviewee - Colin McInnes
No complete success with; there's been a couple of attempts at flying a solar sail. Back in the 1970s, the NASA Jet Propulsion Laboratory had prepared a series concept for solar sailing mission to rendezvous with comet Halley and that failed through, just with the funding issues. More recently that the Planetary Society in the United States had built a small solar sail, but unfortunately the launch vehicle failed, so there has not yet been a genuine solar sail demonstration in space unfortunately.
Interviewer - Chris Smith
Why do you put that sort of indolent stand to because of course this technology sounds like it could offer a huge amount?
Interviewee - Colin McInnes
It could, yeah. I mean, there are two sides to it. There is the push-by engineers, if I can put it that way, who see solar sailing as a fairly a romantic notion of, you know, sailing through space propelled by sunlight and perhaps more hard nosed than that and they really have to identify what are the compelling practical or scientific applications of solar sails and those are applications which will prove the technology forward and again that's in support of things which we've been trying to identify through our work with the European Space Agency and others, the NASA applications for solar sailing in the future.
Interviewer - Chris Smith
And do you have any takers?
Interviewee - Colin McInnes
Through the work for the European Space Agency, we had identified a number of applications such as going to the outer solar system very quickly using solar sails, doing sample-return missions from very high energy objects, comets and asteroids, work which we've been doing with the National Oceanic and Atmospheric Administration in America, the American Met office and their interest in solar sails, where you can use the pressure on the sails to hover station very, very high above the poles of the earth for earth observation and for polar climate monitoring.
Interviewer - Chris Smith
So watch this space, but for the first foray for solar sailing across the cosmos. That was professor Colin McInnes who is at the University of Strathclyde.
(Promo)
If you're looking for highly qualified experienced staff, or perhaps you're looking to make a career move yourself, then why not check out chemistry world jobs dot org, which is a directory with the latest vacancies across the chemical sciences and if you're an employer, you can place unlimited advertisements for both job vacancies or courses for free between the first of July and the 30th of September 2009, but you need to register now. To find out how go to chemistry world jobs dot org.
(End Promo)
Interviewer - Chris Smith
This is the Chemistry World podcast with me Chris Smith. Still to come, how nanotubes are harming the health of plants, fatal fungi and turning table salt into nanowires.
(14:41 -- Super-light molecular sponges soak up hydrogen)
Interviewer - Chris Smith
But first Nina, Scientists have discovered a way to make super light molecular sponges that might soak up hydrogen and we can use them in the fuel tanks of the future.
Interviewee - Nina Notman
So these molecular sponges are porous crystals and they're using it to either store hydrogen or to mop up greenhouse gases like methane and carbon dioxide.
Interviewer - Chris Smith
Sounds intriguing to have a porous crystal. Are we talking about something, I mean, in the past on the Chemistry World podcast, we've talked about metal organic frameworks. These are these interesting structures, where you have metal ions which are then covalently linked to nonmetal ions and the whole thing is like a repeating molecular cage, which has a huge internal volume, so you can store gases in there very efficiently. Is this sort of a spin-off of that?
Interviewee - Nina Notman
Yes, that's exactly right. Since 2005, they've been looking at taking the metal out, so these are covalent organic frameworks and they just contain hydrogen, boron, carbon, nitrogen, and oxygen.
Interviewer - Chris Smith
What's wrong with the metal?
Interviewee - Nina Notman
The metals are heavier. So, its good to have a lighter, for example, fuel tank in your hydrogen fueled car and those are obviously more expensive.
Interviewer - Chris Smith
So you can get rid of them, that's a good thing and so what's the result? Does it work the same, if you get rid of the metal ions?
Interviewee - Nina Notman
Yes, it works in the same, in that the gas is still stored, but in the pores of the crystals.
Interviewer - Chris Smith
What do they look like?
Interviewee - Nina Notman
They consist of building blocks of five or six membered rings arranged into subunits, which are then bolted together with strong covalent bonds to form large crystalline framework.
Interviewer - Chris Smith
How easy are they to make because its easy for us to say, "Oh! Look you just make this molecule and it holds loads of hydrogen or whatever," but is that actually scalable. Can we make that?
Interviewee - Nina Notman
The researchers they say they've been able to make it on a fairly large scale in the lab and they say their synthesis is amenable to scale up.
Interviewer - Chris Smith
Where will be see this applied probably?
Interviewee - Nina Notman
We'll find it hopefully, in the fuel tanks of hydrogen-fueled vehicles and also to mop up greenhouse gases coming out of the plumes of power plant.
Interviewer - Chris Smith
So, it'd be like a molecular sieve. You could just sieve out the gases you don't want to and constrain them inside these molecular sponges, effectively.
Interviewee -Nina Notman
Yes, that's exactly right.
Interviewer - Chris Smith
Thank you Nina.
(16:44 -- Nanotubes accelerate pollutant uptake by plants)
Interviewer - Chris Smith
So lets stick with the very small and James, also potentially doing a pollutants and power plants and things, this is a pollutant linked story, but it is about nanotubes and is actually quite scary.
Interviewee - James Mitchell Crow
Well yeah, its little bit vain, and we hear all the time about how nanoparticles are amazing materials and we can do this and that with them and they're starting to be incorporated into products from paints and cosmetics to antibacterial socks, but the trouble is these things end up in the environment and we're not quite sure what happens to them and what effect they have on the environment once they get there.
Interviewer - Chris Smith
Those wonderful items, someone put together a couple of years ago, big sign like the kind of radioactive danger sign, but it was sort of nanohazard and they're saying that we just don't know what the consequences of these tiny things we pump into the environment is. There might not be one, but on the other hand there might, no one knew asbestos was bad until people started to develop mesotheliomas and lung cancers.
Interviewee - James Mitchell Crow
Well, that's quite the problem and it's very difficult to come up with ways to, sort of, manage the problem, if you don't actually know what the particles are doing in the first place. So this team at the University of Lancaster, Edward Wild and Kevin Jones, they've looked at a small piece of this puzzle and looked at how certain nanoparticles in combination with other pollutants that are out there in the environment affect living plant tissues.
Interviewer - Chris Smith
How have they done it, what were they looking at?
Interviewee - James Mitchell Crow
Well, what they've done is used near infrareds to build up 3-D pictures of a living plant tissue. Near infrared actually penetrates tissue quite well, so they can build up picture 3 to 5 cells deep and what the technique relies on is the fact that some of these particles naturally fluoresce under this wavelength and so they don't need to tag the nanoparticles like and just directly look at where they go within the plant cells.
Interviewer - Chris Smith
So this is done in culture then, have they got a Petri dish and some plant growing in it and you put a sprinkle of nanoparticles on there and then basically see where they go, is that what they were doing?
Interviewee - James Mitchell Crow
Yes, it's essentially that sort of thing. So what they've looked at is multiple carbon nanotubes, titanium dioxide and cerium dioxide and looked at whether that affects the plant's ability to repel, if you like, and phenanthrene which is a common polyaromatic hydrocarbon which sort of comes out of burning fossil fuels.
Interviewer - Chris Smith
Well, that would be in the soils, so that the test here is does this stuff get into a plant normally with these nanoparticles around, does it get into the plant more, indicating that they're some way making the plant permeable to that stuff getting in?
Interviewee - James Mitchell Crow
Exactly right, exactly right. They found with titanium dioxide and cerium dioxide, what these nanoparticles tend to do was just sort of clump together and may be stick to the outside of the plant roots, but weren't really causing any problems, but rather more sinister that the carbon nanotubes are actually acting like tiny hypodermic needles and they were piercing the plant root cells and then effectively acting like a little tube, through which other pollutants in the environment were very quickly then taken up inside the plant.
Interviewer - Chris Smith
What could be the consequence of that?
Interviewee - James Mitchell Crow
That's the bigger question, that's the next question. What this research shows is that all sorts of other pollutants could be taken up by the plant in the similar way, through these little nanotubes.
Interviewer - Chris Smith
I would say though James that one kind of critical thing here is that this is obviously a carefully controlled experiment, presumably not done in real soil, therefore in a real kind of dirt, get your hands dirty environment, so do you think this really will happen in the average garden, the average farmer's field or is this going to be a bit artificial.
Interviewer - James Mitchell Crow
Well, as you said, to be able to monitor where the particle are going, these are obviously all done in the lab, it definitely suggests that in the natural environment, the same process could be occurring and that the nanoparticles could be interacting with other pollutants to have this sort of cumulative effect.
Interviewer - Chris Smith
Which is worrying and it certainly suggests that out of sight mustn't mean, out of mind because scientists absolutely need to follow that finding to discover the true risks, that are associated with working with nanotubes. Thank you James.
(20:53 -- Chemistry in its Element - Erbium)
Interviewer - Chris Smith
And now a special treat in the form of a foray into the realms of our special podcast, Chemistry in its Element, where each week, we take a look at the sometime sinister side of the periodic table and in this episode, UCL chemist, Andrea Sella, looks at the story of Erbium.
Excerpt from Chemistry in its Element
Andrea Sella
A couple of years ago, a colleague popped his head around my door and said as chemists do, "I'm on this ground." It's quite common in chemistry departments who want to do a quick experiment, just want to smudge at something, without having to order a whole bottle. So you ask your friend, whether they've got a bit of whatever, "have you got some Erbium oxide?" "Sure," I said, I got some up in the lab. And a few minutes later, my friend went off with a small bottle containing a delicate pink-colored powder. A few weeks later, I saw him in the stairwell and asked him how he got on with the Erbium. "Its amazing stuff, you have to see this," he replied. He pulled out of his pocket a sample vial containing some stunning pink crystals that glinted alluringly. "Wow!" I said. You can always impress a chemist with nice crystalline products. "It gets better", he said mysteriously. He beckoned me into a hallway that had recently been refurbished. "Look," he said, as the crystals caught the light from the new fluorescent lamps hanging from the ceiling, the pink color seemed to deepen and brighten up. "Wow!" I said again. We moved the crystals back into the sunlight and the color faded again and moving the crystals back and forth they glowed and dimmed in magical fashion. It was a stunning example of the luminescence, which is so common amongst rare earths of which Erbium is a member.
The red phosphor in the fluorescent lights must have contained Erbium on it, and since the emission wavelength of the phosphor exactly matched the absorption of my friend's crystals, resonant absorption was occurring causing the magical glow. The rare earths were revealed to the world quite by accident, by a Swedish lieutenant at Rock Hound Carl Axel Arrhenius in 1787, in a quarry on the island on Vaxholm in Sweden where the small town Ytterby was located. The mineral that Arrhenius had found would lead to the discovery of 16 elements, all them with remarkably similar properties and the small village Ytterby would provide the inspirations for the names of several of them, ytterbium, yttrium, terbium and the element of this podcast erbium. Others got names like scandium, holmium, thulium in recognition of the region once they had first appeared. For over a century, controversies raged amongst the chemists about these elements and one of the key players in this chemical roe was Robert Bunsen, the co-inventor with Gustav Kirchhoff of the spectroscopy. Together they'd had the idea of putting chemical compounds into a flame and analyzing the resulting light with the prism. The spectra they observed proved to be amazing analytical tools. Kirchhoff would use the method to identify elements in the sun. The method rapidly became one of the central pillars of chemistry, but like many others working in the area, Bunsen was intrigued by the faint colors of the rare earth and their remarkable invaria
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