Chemistry World Podcast - January 2011
00:12- Introduction
01:15- No stone left unturned in oil hunt
03:45- Mystery of diamond polishing solved?
06:50- Jack Lifton on the importance of rare earth elements and why we need to conserve them
14:25- Living on Arsenic?
17:10- Nanotube material retains bounce at extreme temperatures
19:16- Stefan Tautz on microscopes that can look at chemical bonds between atoms
26:00- Using fruit flies' sweet tooth
27:45- The medicine's in the (wine) bottle
30:46- Monthly trivia: As pure as snow? Not so
(00:12 - Introduction)
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
Interviewer - Chris Smith
Hello and welcome to 2011 and the January edition of the Chemistry World podcast. With me this month are Phil Broadwith, Andrew Turley and Bibiana Campos-Seijo to discuss why diamonds are harder to cut in one direction than another, why flies could soon replace human taste testers and the wine that doubles as an anti-diabetes drug. I will also be talking to the man who has found the way to visualize the formerly unimaginable.
Interviewee - Stefan Tautz
We realized that if you just look in between the molecules we seen another type of contrast, we see the intermolecular bonds, hydrogen bonds can actually be visualized by this technique.
Interviewer - Chris Smith
That's Stefan Tautz with a discovery that allows him to see the shapes of molecules and even the hydrogen bonds happening between them. I am 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)
Interviewer - Chris Smith
And to kick us off, good news for the oil industry, Andrew.
(01:15 - No stone left unturned in oil hunt)
Interviewee - Andrew Turley
Yes, good news indeed, a group from Rice University in the US led b y James Tour have come with nanoparticles that will hopefully one day be used to detect where oil is hidden in mature oil fields, so oil fields that have already been found and explored to some extent.
Interviewer - Chris Smith
So the big problem being that when we take oil out of the ground we're reasonably good at finding it these days, not terribly good at getting it all out of the ground, so lots is left behind unexploited.
Interviewee - Andrew Turley
Yes, it's a fairly inefficient process something like 60% of the oil in established oil fields has been taken out but obviously that leaves a lot behind.
Interviewer - Chris Smith
Well, nearly half, so what's the new technology and how does it work?
Interviewee - Andrew Turley
Right, so these nanoparticles will filter through the rock and they got with them a kind of tracer molecule which the authors call a nanoreporter that will be released when they encounter oil, so the idea being you put them in one end and recover them in the other end and if they're still carrying the tracer then you can find the oil.
Interviewer - Chris Smith
Is it quantifiable though, because that's the key for the people who want to recover the oil, isn't it? If you put something in it and it reacts with a couple of nano moles of oil and you then get a positive, how can be worth drilling for that?
Interviewee - Andrew Turley
Well it is quantifiable, I mean, I should stress this as a proof of concept stuff. The two components to the tool, one is the particle and one is the tracer and they've been able to measure these two components independently so the tracer was laced with carbon-14 which can be measured radioactively and the actual nanoparticles you can measure using UV spectroscopy.
Interviewer - Chris Smith
And do they reveal in the paper exactly how the oil causes the cleavage?
Interviewee - Andrew Turley
The nanoparticles comprise two parts, essentially hydrophobic core with a hydrophilic outer polymer shell and the tracer is very, very hydrophobic so it sticks to that inner core and when it encounters oil which is incredibly hydrophobic it essentially just leaches out.
Interviewer - Chris Smith
And so this is a proof of concept just in a laboratory, there is not actually any data from an oil field yet to show this can work.
Interviewee - Andrew Turley
Right yeah, this is using rock samples in a laboratory, the authors hope to do it out on the site, that's the plan.
(03:45 - Mystery of diamond polishing solved?)
Interviewer - Chris Smith
Good luck to them. Well from one form of carbon to another Philip. And to the one that people praise almost as highly as oil, diamonds, tell us about this.
Interviewee - Phillip Broadwith
Well yes Chris, well anyone seeing diamond jewellery knows that it's generally highly polished and in multiple different facets to make it sparkle and what most people probably don't know is that it's actually easier to polish diamond on certain of those directions than others and this is a problem for people who want to polish diamonds to make nice uniform shapes but also if you wanted to make very flat sheets of diamond for electronics which is a new and emerging application of diamond, is very difficult because the diamonds that you grow have all sorts of different crystal faces up at that time, so trying to polish the whole thing flat is very difficult.
Interviewer - Chris Smith
Well certainly it's news to me, I did not know that diamonds were easier to cut and polish in one direction than the other, but who has done this and how do we know why now?
Interviewee - Phillip Broadwith
Okay so this is work from Lars Pastewka and Michael Moseler and a group at the Fraunhofer Institute for Mechanics and Materials in Freiburg in Germany. What they've done is detailed computer simulations of what happens when you put a polishing surface across a surface of a diamond and what they found is that as the polishing disc comes across the surface, it loosens the top few layers of carbon atoms, so you get this kind of amorphous layer in between the disc and the surface of the atom and that can drag more atoms out of the diamond surface. The key thing is how easy it is to drag those atoms out.
Interviewer - Chris Smith
So if you've got lots of free atoms sitting there they can form bonds to deeper atomic layers and then pluck out other atoms and that would presumably make it easier to cut that face, but if they can't form bonds readily to other deeper rooted atoms, it's going to make it harder to drag those other atoms out therefore that face will be harder to cut. So is this down then to the orientation or recline of the crystal structure then in terms of its relation to the cutting surface.
Interviewee - Phillip Broadwith
Yep Chris, that's exactly right. So depending on how the face that you're trying to polish is oriented relative to the crystal lattice that will dictate how strongly those atoms are bound in at the surface.
Interviewer - Chris Smith
And you mentioned that this could inform industrial application, because people are using diamonds for all sorts of things now, because they have exciting properties, so does this mean then that we can build better diamond based products knowing this?.
Interviewee - Phillip Broadwith
Well yes Chris, the understanding how to polish the surfaces of diamonds we know lots of ways of kind of growing diamonds, so if we could grow the diamonds so that the right faces are sticking out to make the polishing easier or harder then that would be good. The other thing is that if you want to use diamond in electronics you want a very flat, very uniform sheet of diamond but we can only grow it in very small crystallites so that you end up with a lot of crystals altogether but all of these crystals are of different orientations. So, trying to polish it completely flat is very difficult.
(06:50 - Jack Lifton on the importance of rare earth elements and why we need to conserve them)
Interviewer - Chris Smith
Phil Broadwith and now from rare diamonds to rare earth elements but what actually are they and why they're important to explain here's Jack Lifton.
Interviewee - Jack Lifton
The rarest elements run serially from atomic number 57 to atomic number 71. What defines them is that their chemical properties are so similar that even in nature they're all found together. There is no such thing as a mine for any one of them individually. Everywhere earth mine is a mine for all of the rare earths. What differentiates the different deposits is the relative proportions of some of them to the others and the most common rarer deposits in the world are of the lower atomic numbered ones which are called the light rare earths.
Interviewer - Chris Smith
Are they relatively easy to separate out, given that they are found together like this?
Interviewee - Jack Lifton
No they're not. We used a chemical technique called solvent extraction and this is dependent on the fact that the individual rare earths differ slightly in their solubility between water and selected organic solvents and the real problem is that in order to purify any of them you have to remove all of the others. None of this was done on a commercial basis until around 25 or 30 years ago, prior to that they were used for cigarette lighter flints and for military ammunition, the tracer bullets you've seen in film, climbing into the sky to shoot down the enemy aircraft. The ones you actually see the white flashes were rare earths which catch fire when you expose to the air and so they burn with a white light plus a minor use was polishing glass because Cerium naturally comes as a very, very fine abrasive powder and it's traditional for over a century and a half or so to polish fine optics with this material.
Interviewer - Chris Smith
So that was yesteryear what about today, where are they finding a use?
Interviewee - Jack Lifton
Well today, what happened was around 30 years ago two significant scientific discoveries were made. One is that the rare earth metal lanthanum could be used to make the negative electrode of a storage battery, twice as efficient as a lead acid battery. So, it looked for a brief while like these batteries were going to supplant lead acid batteries but then the cost came in and they're so much more expensive but at the same time the hybrid automotive power system had been invented, a combination of electric and internal combustion drive and General Motors and Toyota all designed hybrid cars based on using this battery which was twice as good as storing energy as lead acid batteries and the rest is really history because today every Toyota Prius, there are now nearly two million of them, uses a lanthanum nickel hydride battery.
Interviewer - Chris Smith
So how much lanthanum actually is there in your average Toyota Prius?
Interviewee - Jack Lifton
In a typical Toyota Prius there is about two and a half kilo of it
Interviewer - Chris Smith
So if there's that many millions of them and the industry is exploding the way it is, can the world keep up.
Interviewee - Jack Lifton
With lanthanum yes, there is no particular worry about shortage of lanthanum. The shortage issue comes from something else. At the same time the battery is developed around 30 and some odd years ago, it was discovered that the strongest possible permanent magnets could be made from the rare earth metal neodymium, Neodymium is a mid range mid-weight rare earth metal. Unfortunately, it's one of the more terminal ones. And it was discovered that a neodymium ion-bond alloy could give you a magnet on a weight for weight and size for size basis much more powerful than an iron-based magnet. This allowed motors to be miniaturized and electronic generators to be made much smaller. This has become the more significant of the rare earths today. The automotive industry and what they call under-the-hood applications, today uses around 40% of all the neodymium produced just in the world automotive industry and this use is growing. Each electrified car uses about a kilo of neodymium and okay two million kilos is 2000 tons and it's not much neodymium at this point, but if the automotive industry is assumed just going to double in size in the next five or six calendar years, that would mean doubling the demand for neodymium. With today's production neodymium we would not be able to sustain doubling of the size of the world automotive industry so that has to increase, but there's an even more serious problem. In order to make these electric motors and generators as small as possible, reducing the weight of the components, you need to modify these neodymium ion bond magnets with the rare metal dysprosium and whereas neodymium is produced at the rate of about 20,000 tons a year, dysprosium is only produced at the rate of 1000 tons a year, but the under-the-hood applications for automotive require a ratio of 1 to 10 of neodymium to dysprosium. Production of dysprosium is just now keeping even.
Interviewer - Chris Smith
So you've mentioned and I am very glad you brought this out the question of production and how much of the stuff we are consuming but what about global production. Where do the majority of these rare earths actually come from? Who is making them?
Interviewee - Jack Lifton
At the moment 97% of the rare earths are produced in China, in the Peoples Republic Mainland China. We have two large mines coming on stream in the West. One is Australia by Lynas Corporation and the other one in California Molycorp, but neither one of those mines can produce dysprosium. The Chinese say that they do not have sufficient reserves to increase their production. They've said this quite often
Interviewer - Chris Smith
Do you believe them, because of course that China could just be saying this to gain a commercial upper hand, it wouldn't be beyond the realms of possibility?
Interviewee - Jack Lifton
Correct, I am not saying that I believe them. Chinese exploration geology is not very well developed. They don't know what they've really got. So they could be telling the truth and not the correct. On the other hand they might be doing this for commercial advantage of course. No one knows. But in the meantime this is a driver for a number of deposits in Canada, in South Africa and one in the United States which have significant dysprosium. The world needs additional production of heavy earths, whether the Chinese or wrong or not telling the truth, we still need the material.
Interviewee - Chris Smith
Well that's the price of progress. That was rare metals consultant Jack Lifton.
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Interviewee - Chris Smith
You're listening to the Chemistry World podcast with Phil Broadwith, Andrew Turley, Bibiana Campos-Seijo and with me Chris Smith. Still to come the rubbery material that stays bouncy even at 1000 degrees, but what can we do with it? First though the bacteria that can issue phosphorous in favour of arsenic. Phil.
(14:25 - Living on Arsenic?)
Interviewee - Phillip Broadwith
Well this is some research done by a group at the Arizona State University led by Felisa Wolfe-Simon, what they've found is that they can take a certain breed of bacteria from a lake and grow it on a medium that has a lot of arsenic in it and very little phosphate, almost no phosphate and then phosphate normally one of the six elements that you would absolutely have to have to sustain life. So what this is kind of showing is that there's possibility that there are bacteria that can use arsenic instead of phosphorous to do their metabolism.
Interviewer - Chris Smith
But having said that since this came out huge splash in the journal Science when it came out and all around the world in the press subsequently, the people have now said well actually is this all is cranked up to be.
Interviewee - Phillip Broadwith
In fact the media splash started before the paper had even come out when this research has been done in association with NASA and NASA put out a press release saying there's a possibility that this will lead to us being able to find extra-terrestrial life and that got everybody very excited with a lots of speculation and when the paper came out, people didn't necessarily look exactly at what the paper was specifically claiming.
Interviewer - Chris Smith
Indeed, there has sort of been a subsequent trial by blog, hasn't it, the blogosphere have been dissecting and disentangling what's going on in this paper and something had been pretty critical, because I was scanning through the arguments that people were making and they were saying things like, well if you look at these bacteria they don't exactly look healthy, there's no evidence that actually they have completely replaced the arsenic for the phosphorous and so on.
Interviewee - Phillip Broadwith
Well yes and what Professor Wolfe-Simon has said is that they're not specifically making claims that the bacteria can survive in a complete absence of phosphorous, they're saying yes there's possibility that there's still trace phosphate there, what the main thing is that the bacteria are not dying, in fact they're growing quite well in the presence of all of this arsenic.
Interviewer - Chris Smith
It doesn't really surprise me that much though, to be honest because if you go to the Gulf of Mexico right now, you'll find bacteria that are thriving on crude oil, if you are someone to bacteria crude oil naturally, they would have said no, but the fact is that there are bacteria which if they're exposed to something for long enough will evolve to accommodate that particular source of sustenance, I don't think it's really any different here. The lake that they got this bacteria from is very enriched for arsenic.
Interviewee - Phillip Broadwith
The difference here is that crude oil is just another source of carbon whereas phosphorous was believed to be absolutely essential for life and what this is saying is that to some extent these bacteria can substitute arsenic for phosphorous, whether or not this is actually incorporated into their DNA and whatever else is yet to be completely proved and Professor Wolfe-Simon has said they want to work with more people to kind of clarify all of that.
(17:10 - Nanotube material retains bounce at extreme temperatures)
Interviewer - Chris Smith
If one thing that's very small, bacteria to something odd as magnitude smaller again Bibi tell us about these nanotubes. What is this about?
Interviewee - Bibiana Campos-Seijo:
A group of researchers in Japan at the National Institute of Advanced Industrial Science and Technology in Tsukuba have been working with carbon nanotubes and have made a rubber-like material that remains usable in a temperature range of about 1000 degrees.
Interviewer - Chris Smith
So, a very big range, how does this compare with all sorts of rubbery materials or sealing type materials that we currently have and concurrently use at the moment?
Interviewee - Bibiana Campos-Seijo
The most probable one seems to be silicon rubber and there's no comparison really in terms of the temperature range, because for silicon we are talking about -50 to 100 degrees, when you take it out of those temperatures it breaks down or it hardens as well.
Interviewer - Chris Smith
So this is a significant step forward in terms of the temperature range.
Interviewee - Bibiana Campos-Seijo
Definitely, we are talking about a temperature range of -196 to in excess of a 1000 degrees, so it is a significant improvement.
Interviewer -Chris Smith
Before we come on to what you might possibly be able to do with such a sealant or such a rubbery chemical, how do they actually make it?
Interviewee - Bibiana Campos-Seijo
The team were working with forests of carbon nanotubes and by modifying the catalysts during chemical vapour deposition, they were able to create random networks and when they then investigated the mechanical properties, they found that they were visco-elastic which means that they have a consistency like honey but then they have elasticity as well.
Interviewer - Chris Smith
Well, what could we do with this? Are there any applications at the moment industrially crying out for a chemical that can behave this way?
Interviewee - Bibiana Campos-Seijo
Well, it seems that we have a solution of what our problem that hasn't been set out yet, because what this group are saying is that the material has very interesting properties but they don't want to develop it any further until they find industrial applications and so far they haven't done that yet, so I think that's the next step for this group. They will try to determine how they can use it and then they will improve on the material and the properties.
(19:16 - Stefan Tautz on microscopes that can look at chemical bonds between atoms)
Interviewer - Chris Smith
So very much a solution albeit an elastic one in search of a problem, thank you Bibi. And now from the nanoscale to something even smaller. The bonds between atoms. Here's a man who's found a way to actually see them.
Interviewee - Stefan Tautz
My name is Stefan Tautz and I am working at the Forschungszentrum J?lich. So, what we were doing is that we were trying to actually contact individual molecules with a scanning tunnelling microscope, the scanning tunnelling microscope is a microscope but it has much more capabilities, it can even manipulate individual atoms and molecules and in this particular experiment we really tried to take a single molecule and to contact it with STM and during these experiments of course you have to image again and again these layers in order to find the molecules which you would like to contact and at some stage, we actually got this very nice resolution which we've never seen before and yeah, we were sort of stunned by what we had seen.
Interviewer - Chris Smith
So what did you see?
Interviewee - Stefan Tautz
So we saw actually the chemical structure of the PTCDA molecule which is a perylene derivative we have used a lot as model molecule for organic and molecular electronics because it is quite well behaved, it can be deposited very nicely on solid surfaces and so on and from that time on we said we must understand why suddenly these nice images came about and this took us then a few months actually to figure out that it was hydrogen which had got caught between tip and substrate and changed the imaging properties of this experiment in a drastic way.
Interviewer - Chris Smith
Can you just explain how you set this up, so how do you physically do the experiment? Where do you put the molecule that's under scrutiny and then how do you survey its surface?
Interviewee - Stefan Tautz
So what we do is we prepare our molecular layer by evaporation of PTCDA molecule for example and then before we can then actually do this modified operation mode using the hydrogen we have to flood the chamber in which the STM, it is actually a low temperature STM working at cryogenic temperatures below 10 Kelvin with molecular hydrogen gas and since the STM and all surfaces in the STM tips the substrate are cold, this gas will actually condense and freeze off on the surfaces of the tips and also of the sample, this hydrogen then in between tip and sample we can get this nice imaging.
Interviewer - Chris Smith
And so physically the microscope is picking up the current that's flowing between the tip and the target molecule or is it picking up something else?
Interviewee - Stefan Tautz
It is actually I mean the scanning tunnelling microscope would really register the tunnelling current between tip and substrate, that's true.
Interviewer - Chris Smith
So what is the hydrogen doing?
Interviewee - Stefan Tautz
The hydrogen is in fact acting as a little sensor in this tunnelling junction. It is if you like loosely suspended between tip and sample and if you then scan the tip across the sample this hydrogen molecule feels the repulsion from the substrate from the molecules, the PTCDA molecules which we are imaging and this repulsion means that the position of this hydrogen molecule from place to place above the substrate will change a little bit and this change will in fact affect the electronic structure of the tip and this in turn effects the tunnelling current which we measure.
Interviewer - Chris Smith
And what sort of resolution is this capable of? When you image these molecules are you literally just seeing little hot spots where say the carbon atoms are and the hydrogen, or can you physically begin to probe the interaction or bonds between those individual atoms?
Interviewee - Stefan Tautz
Well we found that actually two things are possible. First of all the resolution which we can get we estimated from the sharpness of the image this is around 50 picometre, so it's actually very good and what we see mainly is sort of the backbone of sigma bonds within the molecule and this then leads to images which clearly show the hexagonal structure of the aromatic system of our target molecules. This is one thing but then we realized that we just looked in between the molecules we see another type of contrast and this by comparison with theoretical calculation, it shows that we see intermolecular hydrogen bonds can actually be visualized by this technique and this is something that we got very excited about. The mechanism of actually looking at those hydrogen bonds is not to so well understood, so there we still have to do some work and this work is currently being conducted.
Interviewer: Chris Smith
Because understanding the hydrogen bond would give us insight into all kinds of exciting things. How proteins fall, why ice behaves the way that it does, why water has the strange properties that it does, so it's incredible to think that you can actually see something which was very much of theoretical phenomenon up until I suppose you did this.
Interviewee - Stefan Tautz
Yeah, absolutely I agree with you and of course we are only just at the very beginning of this, I mean we have seen that this is possible, we have now started some collaboration with the theoreticians who tried to give us hints, why it is actually that we see those intermolecular bonds; but I mean the examples which you quoted like proteins or water layers, these are things which one could possibly try this technique although one has to say of course that being based on STM it will suffer from the general problem which all organic probe method test has. As soon as you have a sample which is not flat anymore but has a freedom internal structure then it becomes difficult to image because the tip cannot actually access the troughs and the grooves of this object. So this would be a qualification as far as the application to proteins is concerned but on the other hand, there are people who use scanning probe methods to image and mobilize proteins, so if that is possible with AFM or traditional STM which will be possible, this our method here with STM and I am sure images will result which tell us much more than we've been able to see up to now.
(26:00 - Using fruit flies' sweet tooth)
Interviewer - Chris Smith
Incredible that was Stefan Tautz from theForschungszentrum J?lich. And now are flies about replace human taste testers, Andrew?
Interviewee - Andrew Turley
Well I am not sure of giving up the human tasters entirely but there's a remarkable feature of Drosophila which is very commonly studied type of fruit fly that it has very similar preferences in terms of the sweet things it likes very similar to humans and these researchers at the Commonwealth Scientific and Industrial Research Organization in Queensland led by Ann Ray have been exploiting this similarity.
Interviewer - Chris Smith
So how did they do it, you get a fruit fly to drink some sugar solution and see which ones it likes and which ones it doesn't or have they go
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