Chemistry World podcast - September 2013


Audio Files

The Chemistry World podcast is sponsored by Waters – world leaders in innovative analytical science solutions. Visit waters.com for more information.

1.10 A team in the US has developed a detection system that crime scene investigators can wear on their fingertips to rapidly identify suspected traces of explosives and gunshot residue. - Forensic fingers

4.11 US scientists have developed the first efficient and scalable route for the total synthesis of ingenol – a plant-derived diterpenoid used to treat precancerous skin legions. The work offers cheaper and faster production of the drug than the current, inefficient plant extraction route, and could pave the way for the chemical synthesis of many other complex natural compounds - Total synthesis outshines biotech route to anticancer drug

The grossly warped nanographene has interesting optical and electronic properties © NPG

7.47 Do we have enough science graduates, or are there too few jobs for the graduates we have? Around half of university entrants are studying STEM (science, technology, engineering & maths) subjects, so Emma Smith surveys the employment landscape and prospects for chemistry graduates - Measuring the job market

15.28 Maxwell’s demon is a famous thought experiment designed to show how, in an isolated system, disorder or ‘entropy’ can decrease in apparent violation of the second law of thermodynamics. Now researchers in the US have put a new twist on the idea, claiming to show theoretically how the second law can remain intact if the demon is allowed to scribble down random information - Maxwell’s demon gets scribbling

19.05 Nanoparticles that never have to enter the body can capture harmful components in blood, scientists in Switzerland have shown - Nanomagnets clean blood

21.41 While overt gender discrimination is less common today, women are still leaving chemistry in greater numbers than men. Polly Arnold looks into the causes of the leaky pipeline – Stemming the tide

The scientists were able to tell the genuine article from a fake thanks to the inks used © ACS

28.46 A new family of nanocarbons has emerged with the growth of the first non-planar nanographene. Chemists from Boston College, US, and Nagoya University, Japan successfully synthesised a grossly warped nanographene by embedding non-hexagonal rings into a nanographene subunit - Chemists welcome newest member of nanocarbon family

32.24 Italian scientists have uncovered a new dimension to the art of stamp collecting by analysing the paper composition of the entire issue of Italian postage stamps of the last 150 years - Spectral library chronicles chemical evolution of Italian stamps

35.39 - Trivia - Why were syphillitic rabbits celebrating on the 31st August 1909? Here's a clue!

Full transcript

Interviewer - Meera Senthilingham

This month forensics on the go, using nanomagnets to clean your blood and a leaking pipeline of women.

Interviewee – Polly Arnold

Women just drop out of the career progression point, you get this decrease in percentage from about 50% of undergraduate chemists down to what is about 9% in all subjects, even biology, biosciences by senior professorial level.

Interviewer - Meera Senthilingham

Polly Arnold will be discussing why this occurs and what can be done about it later in the program when we also hear about graphene pringles, new ways to synthesize anticancer drugs and using infrared to spot counterfeit stamps. That's all to come in this Chemistry World podcast, sponsored by Waters, World Leaders in Innovative, Analytical Science Solutions. Visit waters.com for more information.

Interviewer - Meera Senthilingham

Hello, I'm Meera Senthilingham and also with us for this the September 2013 edition of Chemistry World are Patrick Walter, Phil Robinson, and Neil Withers, who's been looking at faster ways of solving crimes using his fingers.

(1:10 - Forensic fingers)

Interviewee - Neil Withers

That's right, a team from the University of California in San Diego have created some forensic fingers as they call them, which allow them to detect gunshot residue and explosives at a crime scene in just a few minutes.

Interviewer - Meera Senthilingham

So, why is this useful to have this on the fingers, what's the current method?

Interviewee - Neil Withers

So, the current method, you go to a crime scene you have to go and collect lots of little bits of residue from literally everywhere in the apartment or wherever you're doing it and then you have to send this stuff away to a lab and then it gets tested, so, it takes a long time.  And the problem is gunshot residue doesn't stay around forever, it’s only found in very small amounts. And once you've found it, you have to send it away to a lab that takes a long time to analyze and get back, so, it’s all a problem. So, what Joseph Wang and his team have done is they've created a sensor that you put on a little finger part of a glove, so that's an electrode on the finger and then on the thumb of the glove is an electrolyte. So, you go around with your finger like the people in sitcoms do on mantelpieces and you can test and then you press your thumb and finger together. As the electrode needs the electrolyte, you cause a little reaction and the circuit gets completed. Then you take your bit of glove over to your small portable electrochemical detector which can tell you, almost instantly, whether it is gunshot residue or just dust because you haven't dusted frequently enough.

Interviewer - Meera Senthilingham

So, essentially, just as you say people sweeping around in an apartment, it all just happens instantly then and there to see the reaction.

Interviewee - Neil Withers

Yeah, the team says it takes about four minutes to do and they tested in on lots of different things in the lab, lots of different surfaces.  They didn't even clean their things so as it’s a normal lab, it probably had who knows what, on bits of wood, on glass, on paper. And they were able to get pretty clear detection of whether there were explosives or trace amounts of either gunpowder or bullets and whatnot because there's lead and bismuth and other heavy metals. So, they were quite easy to detect. The important thing of how they've done this is the electrolyte that I've mentioned on the thumb of the glove is a solid, a solid gel, an ionic gel and so because this means you don't need any water or solvent, it’s all very self-contained and it’s much more stable and it’s much more transportable, you don't have to worry about things evaporating or anything like that. So, that’s one of the key advantages.

Interviewer - Meera Senthilingham

And so they've tested this after that at various places in the lab and is it likely that it could be in use?

Interviewee - Neil Withers.

Well, they seem to think so.  They actually went to get their residue from the local shooting range - I guess in America they are more common than they are here - and they put them on different places in relatively normal environments thatweren’t pristine and it seemed to work quite very well. So, forensic fingers crossed who knows, it might be in use soon!

(4:11 - Total synthesis outshines biotech route to anticancer drug)

Interviewer - Meera Senthilingham

And so from a quicker way to do forensic analysis to a quicker formation of drug and anticancer drugs specifically, Pat?

Interviewee - Patrick Walters

Yes that's right. So chemists in the US have got one over on their biotechnologist colleagues by making a drug both quicker and more inexpensive.

Interviewer - Meera Senthilingham

So, what's the drug here?

Interviewee - Patrick Walters

So, the drug is ingenol, which is sold as Picato. It’s a drug used to treat precancerous lesions in a disease called actinic keratosis. This drug helps to kill rapidly dividing skin cells and these lesions are the result of too much sun, so if you spend a long time sunbathing, soaking up the rays, you can pick up a few these odd shaped lumps and bumps that you need to get sloughed off by this particular drug.

Interviewer - Meera Senthilingham

And how is ingenol usually produced and what are the limitations that needed improving then?

Interviewee - Patrick Walters

So, ingenol actually comes from a very common garden weed. If you're a bit green fingered and do the gardening, you would have seen this around. It grows easily in disturbed soil, so as soon as you dig something up, these weeds will come through. At the moment, the extraction process is rather long-winded.  So, you only get a few milligrams out of a kilogram of this weed, whereas say for something like artemisinin which is the anti-malaria drug, this is also controlled or limited by the amount you can get out of sweet wormwood. In this case, for artemisinin, you can get a gram or so out of a kilogram, so it’s even lower yield so this is a real problem for actually solving synthesizing this drug.

Interviewer - Meera Senthilingham

So, the challenge is really to try and make this in a more efficient way, so what's happened and who's been working on it?

Interviewee - Patrick Walters

So, organic chemistry wunderkind, Phil Baran at the Scripps Research Institute along with his group have succeeded once again in slimming down a very complex synthesis, so ingenol has actually been made before by Jeff Winkler at the University of Pennsylvania. He managed it in 37 steps so that's quite an unwieldy synthesis and also it wasn't made from simple nice cheap starting reagents. Now Baran and his group have managed to get it down to 14 steps and they start with a nice common, carbon backbone structure which is careen, which is commercially available, easy to get hold off and it’s cheap.

Interviewer - Meera Senthilingham

So, what's the actual process to go from them to get ingenol in?

Interviewee - Patrick Walters

So, just like the plant, milkweed, the Baran group took a two-phase approach to actually building up the structure. So they start with carene - the commercially available, cheap and inexpensive carbon backbone - and they add more and more carbons to it, actually building it up to create this skeleton. In the oxidase phase, they add to it, so they're adding all the oxygen moieties to it to finish off the drug.

Interviewer - Meera Senthilingham

So, what needs to happen next, would they want to get even fewer steps or what's the actual next stages to make this the main source of this drug?

Interviewee - Patrick Walters

Well, the company that makes Picato or ingenol is LEO Pharma, a Danish Pharma company. They're already interested in this. They're working with Baran's group and they're actually planning to scale it up. So, I'm sure they'll be interested in chopping off a few more steps here and there but they're already moving towards the production stage. Actually cutting out the whole biotech route, the entire extraction from milkweed and then they're going to go straight down the totally synthetic route to actually make this drug. So, hopefully in the future it'll be cheaper and that’ll be faster to make.

(7:47 - Measuring the job market)

Interviewer - Meera Senthilingham

Thanks Patrick. Now the scientists working on the findings and discoveries that we discuss here each month all share a passion for science, something governments and institutions have been trying to increase in the next generation by endorsing outreach activities in the field of STEM - Science, Technology, Engineering and Maths, something Emma Smith has been investigating the impact of.

Interviewee - Emma Smith

I'm interested certainly in terms of who studies STEM subjects at post compulsory level so that would be, for example at A level through higher education. We particularly focus on undergraduate level and then the next stage in the pipeline would be postgraduate studies and then some of the work that we'd be looking at the moment onto early career destinations.

Interviewer - Meera Senthilingham

And so what were you really seeing then? Who is going into become STEM graduates in the first place?

Interviewee - Emma Smith

If you're looking particularly at the traditional sciences: chemistry, physics and biology which is where we focused, these are difficult subjects in school, not all students succeed in these subjects. These are considered to be, you know, at least high status subjects and they are socially stratified, certainly in the school curriculum as perhaps you might expect. What I suppose has been interesting is the gender differences in terms of A level where, in chemistry for example, very similar numbers of men and women study A level chemistry. It’s not gender segregation to the extent as it is in physics, in terms of the male majority and biology to some extent is with women. Looking for example, in terms of participation in higher education more broadly, I think what is interesting is that around half of university entrants study STEM subjects, if we define STEM as broadly as possible, and not largely consequences of expansion in the numbers studying subjects like psychology, sports, science, computer science and so on. So, these sorts of more applied STEM subjects are very healthy in terms of numbers going to university to study them.  And interestingly if you're looking in terms of higher education, participation at the undergraduate level with the pure subjects: One figure that’s particularly striking is  intensive participation in physics where around 3000 roughly, students have studied physics (per year) at universities since the late 1980s and that number has really hardly varied. So some of these subjects seem to be relatively resistant to initiatives to try and get more and more people who study these areas.

Interviewer - Meera Senthilingham

So, we have seen these core subjects, as you mentioned, they're resistant to increases in numbers, subjects like physics. So you see department closing or merging and so on. Why do you think they are resistant and what are the consequences then of them not increasing in number whilst the other applied sciences are?

Interviewee - Emma Smith

You could argue that those who were studying the core sciences or pure sciences are highly qualified students and they tend to be successful in these subjects.  And because they tend to do quite well in school, they are usually seen to likely to have gone to university anyway.  So, they're less likely to be affected by widening participation initiatives, perhaps newer subjects, for example sports science, for many students it’s a relatively new subject. It’s not a subject that perhaps they had been less successful at in school, and so may be in those subjects, the expansion of higher education has perhaps channelled into those students.

Interviewer - Meera Senthilingham

And then what do you think then are the consequences of all of this? Because there are more graduates in certain areas compared to others, do we as a result therefore have enough qualified STEM graduates out there? Or do these core areas need more graduates? What are the effects of this increase in one area and this resistance in the other?

Interviewee - Emma Smith

That's a really difficult question to answer. I think any debate around shortages are complex. A lot of the anecdotal evidence tends to focus on demand: employers reporting not being able to fill job vacancies, which is obviously a concern. In our research, we try to focus on the supply which is easier to look at - we can count numbers and we can look at what they have studied and what are their trajectories. We focused really on what STEM graduates do within six months of graduation and looked at those patterns over a reasonable period of time. We've managed to get data that goes back to mid 1990s. The patterns again tend to be quite flat. Around about 10% of graduates are unemployed six months after graduation and if you look at STEM subjects overall, that figure is still around 10%.

Interviewer - Meera Senthilingham

I mean the ones that are going into employment, are they going into employment that say uses their STEM background.

Interviewee - Emma Smith

I think that varies quite considerably between different subjects. So, if we looked for example at chemistry, around about a quarter are in what we might consider non-graduate jobs. Occupational classifications that would be more elementary personal service occupations, caring, sales occupations and so on, elementary occupations. Around a quarter of chemistry graduates go into those sorts of jobs. So it’s a relatively high proportion. However, on the other hand, around about a third goes straight into professional jobs. So the picture is quite mixed. This of course is only six months after graduation. We don't have the data here to know what happens to them later, that’s the sort of work that we're going to be doing in the coming months.

Interviewer - Meera Senthilingham

So this is data about the UK population and graduates here, do you know much about what this reflects globally? Is this is a similar situation globally, do you know?

Interviewee - Emma Smith

Certainly, the literature, the debates that we have in the UK are reflected in the US and Australia and the Europe. And the US is quite interesting because of course they have a much broader undergraduate program than we do. They specialize a lot later than we do in this country. The debate about STEM shortages are very similar in the US as they are in this country and arguably this kind of historical debates around the quality of the STEM workforce has a strong place in the US education history, with the space race and Sputnik.  The impact that has had on education policy in US is quite pronounced really and so this is not a UK phenomenon and it’s not a new phenomenon.

Interviewer - Meera Senthilingham

And so I guess this kind of insight should be used to guide policies towards education and curriculum in the future?

Interviewee - Emma Smith

Yes and I think it is interesting with the new national curriculum, although not all schools will have to follow. There seems to be a move towards students studying more science and also sort to enforce the distinction in separate sciences, chemistry, biology and physics. The concerns are that will further reduce the potential pool of people who could study the sciences beyond the compulsory levels.  And particularly, certainly the evidence at the moment suggests that students on free school meals are less likely to study those subjects, the separate sciences. So if those subjects are seen as the gateway for further qualification then it could lead to further inequalities in the system. I have a really nice quote. It was written in the late 1960s about students from science. And it says that ‘if science were compulsory, it must be attractive; if it’s not attractive, it will only suffer if it’s made compulsory and if it were attractive, it wouldn’t need to be compulsory. So that summed up maybe the status of science in schools at the moment.

Interviewer - Meera Senthilingham

Emma Smith, Professor of Education at the University of Leeds. You're listening to the Chemistry World Podcast, sponsored by Waters with me, Meera Senthilingham. Still to come, graphene pringles and a new way to spot counterfeit stamps but before that a demon of chemistry has been realized: Maxwell's demon, going against the laws of thermodynamics, Phil?

(15:28 - Maxwell’s demon gets scribbling)

Interviewee - Phil Robinson

Maxwell's demon is a fault experiment that was proposed by James Clark Maxwell, a Scottish scientist/engineer really who was instrumental in the field of thermodynamics. Maxwell's demon relates to the second law of thermodynamics which states that the energy or rather the entropy, of an isolated system must always increase. So, to put it another way, in a way that relates to this experiment, a cold body will not pass heat to a warm body. If you have a cold and hot body together, then they will reach thermal equilibrium, you won't have one continuing to get colder and the other one continuing to get hotter, that's in violation of that rule and that relates to entropy. So, Maxwell proposed this thought experiment, wherein if we have two chambers that are connected by a gate and sat at that gate is a demon, a being, an intelligent being that could discern the speeds of these molecules which is related to their temperature or their energy, if you like, and he'd only admit, to one chamber, the faster moving molecules and to the other chamber the slower moving molecules. And in so doing without any work being done on that system, you would create a temperature differential, one vessel would get hot and hotter and the other would get colder and colder.

Interviewer - Meera Senthilingham

But, so how can that account to that?

Interviewee - Phil Robinson

Okay well, it’s probably simpler we go on to explain the proposal that we now have from these scientists. So, this is Christopher Jarzynski at the University of Maryland in the US and his proposal is to create almost exactly this system that we described as Maxwell's demon experiment although the demon in this case is not a intelligent being, it’s just a device, a device that interacts with two heat baths, heat reservoirs but that also interacts with a memory strip if you like.  So, if you like we give Maxwell's demon a notepad and we ask him to write down his choices. In that, because information is related to entropy, the entropy increase that Maxwell's demon makes on this memory strip on this notepad, accounts for any entropy decrease that he causes in the system, in moving heat from a cold body to a warm body. So, whenever energy is transferred, in this system that they propose, whenever energy is transferred from the cold to the hot reservoir, the device makes a change to the memory stream, makes a note on the notepad, and so the increase in the entropy of the memory stream accounts for the decrease in the entropy in the reservoirs.

Interviewer - Meera Senthilingham

Therefore balancing things out.

Interviewee - Phil Robinson

Essentially yes. So essentially we balance the entropy decreases and so the second law is not violated.

Interviewer - Meera Senthilingham

And so from separating hot and cold molecules,now to separating things in our blood and getting rid of toxins in our blood, Neil?

(19:05 - Nanomagnets clean blood)

Interviewee - Neil Withers

That's exactly right. Swiss scientists from Zurich have used nanoparticles to clean blood, take out toxins as you say, without the nanoparticles actually entering the body. And that's the crucial thing because a lot of people are quite concerned about the effects that nanoparticles might have in the body and then later in the wider ecosystem once they leave the body.

So what the teams led by Wendelin Stark and Beatrice Beck-Schimmer, both at different Institutes in Zurich, have done is they, it’s a bit like dialysis really. They've taken a rat and they've diverted the blood out of the rat and they add into it nanoparticles of iron, coated with different things and the nanoparticles are able to attach to lead and digoxin which is, one is a drug and the other is a nasty heavy metal. So they pick out the bad things out of the blood and before the blood goes back into the body, the team used a magnetic separator to take out the nanoparticles which if you remember have got iron in the centre, so are magnetic, so they're attracted to the big magnet around the outside. And then the blood is able to go back into the rat without the lead, without the digoxin and crucially without the nanoparticles.

Interviewer - Meera Senthilingham

So, essentially they're just picking it up and then you're taking nanoparticles out before the blood re-enters the body.

Interviewee - Neil Withers

Yeah that's right and to make sure that they haven't got any of the iron left in the blood, the nanoparticles in the blood, they coated the particles with carbon which stops it oxidizing in the blood, because obviously there's oxygen and all sorts in blood, so that stops them turning into things that are less magnetic. And they also put a little bit of platinum in the particles as well, because obviously there's a lot of iron in blood, so once it had gone back into the rat, they wanted to make sure that there weren't any particles in there, so if they'd looked for iron then they would've seen iron but if they look for platinum and they don't see any they don't, they know, that the blood is clean again.

Interviewer - Meera Senthilingham

And so what is the reality of this being use on humans, so it’s very much on rats at the moment.

Interviewee - Neil Withers

I'm not sure to be honest. As you say, it is at a very early stage. But I guess the fact is that dialysis is such a commonly used technique, so there is the infrastructure for that part of it to happen. Also, nanoparticles can be functionalized with many, many different things that can be attracted to many, many different things.  So, I think there's a wide possibility for it to be used in lots of different applications if it can all come together and work probably.

Interviewer - Meera Senthilingham

Thanks Neil. Now we heard earlier about initiatives to get more people interested in science at the undergraduate and postgraduate level. But if these numbers do increase, one problem still remains and that's the number of women that stay on after this postgraduate level to pursue a career in chemistry and in science as a whole. A leaky pipeline is known where women simply drop off along this career path and Polly Arnold has been exploring why this happens.

(21:41 - Stemming the tide)

Interviewee - Polly Arnold

So, the leaky pipeline is a really nice phrase that describes, in fact, for all scientists and all STEM subjects. It describes that depressing drop off that we see at every single stage from school through to senior professor where women just drop out of the career progression points. So, you get this decrease in percentage from about 50% of undergraduate chemists perhaps down to what is about 9% in all subjects. Even biology and biosciences, we still see this pipeline leaking women down to about 9% by senior professorial levels. The subtleties of the reasons for it really struck me as we started to do more and more research into this.

Interviewer - Meera Senthilingham

And so what were the reasons?

Interviewee - Polly Arnold

Well, if it was a simple problem then we would have solved it by now. So, there's a multiple set of reasons and they can't be different between different subjects. So issues like concern over whether your job is going to be secure or not, is not a worry to physics postdocs but it’s a worry to chemistry postdocs. Perception of bias by someone against them can be almost as powerful as a genuine bias against them. Then this other problem we have where men and women suffer from this unconscious bias of just thinking that a man is more likely to demonstrate leadership or better skills or be valued for their skills more than a woman in a given profession. We've seen this in several different areas. The study has also been done in business, in the world of business too.

Interviewer - Meera Senthilingham

So, how did you actually set about getting these findings, how did you study for this insight?

Interviewee - Polly Arnold

We'd read a lots of documents that have been written by the Royal Society of Chemistry and the Royal Society of Edinburgh, the Institute of Physics and all of these studies that has been done come to present a lot of these issues, a lot of potential problems and possible solutions. That could involve things like childcare issues for people and monitoring numbers of people applying in the first place to things. What we were trying to do here was work out whether the large numbers of women that we had Edinburgh was down to something particular that we'd done that would allow us just to bring out something special about what we were doing. So, we interviewed a lot of people, we sent out lot of questionnaires, we had some wonderful stories back from alumni, both positive and negative about their times both here and afterwards and disappointingly, we didn’t, well I guess exactly the same as what everybody else finds, we didn't find the perfect solution, the perfect answer for what you have to do.

Interviewer - Meera Senthilingham

What were the main issues that did come in through, you talking to all of these alumni?

Interviewee - Polly Arnold

So the key things that people worry about are their concerns of whether they will be able to have a career that allows them to pause and have a child and get back in. They simply don't think they're good enough and nobody has ever told them that they are good enough and that's really a key one I think in this. They also see the way people are working all the time and they think they don't really want that job and may be something else will be better.

Interviewer - Meera Senthilingham

Focusing in on what could be specific to the chemical sciences. Would you say there is a gender bias in the chemical sciences, specifically?

Interviewee - Polly Arnold

Yes. There's definitely a gender bias in the chemical sciences, we have all the data that prove that. We're trying to fix it and a lot of people are working very hard to fix it, not just women and it shouldn’t be the people in the senior positions in the universities as well, well not just universities, across also industry. It should be across the board that we worry about these things.

Interviewer - Meera Senthilingham

At what stages would you say the real gender biases lie?

Interviewee - Polly Arnold

I've argued with colleagues over this when we've looked at the angle that the leaky pipeline shows for different subjects and at which point there's the steepest decline. For me, I think in chemistry it’s about the postdoc level where people are really thinking about ‘can I bear yet another move’ and ‘how long will my next postdoc be for’ and ‘will it be a fellowship or postdoc?’ I think that's probably the point where maybe their biological body clock is starting to tick as well, or maybe they’re really suddenly starting to look at the supervisors that they have and thinking, well I’m not sure I want that job after all. It really enhances your CV if you can make a significant move either in subject or in geography, so that you see a very different lab environment and this movement often generates a lot of fear in people who are maybe just starting to settle down or trying to solve the two body problem: trying to get two people in two jobs in the same place for long enough that they can start a family or feel like they're embarking on something that's going to be more like a stable life.

Interviewer - Meera Senthilingham

How would you say then through your findings of this and the specifics of the scaling up of professions in chemistry, how can all this be addressed to try and improve the gender bias in the future?

Interviewee - Polly Arnold

Well firstly, I’d like to change society so that we don't have this automatic assumption that it’s going to be the woman that does the majority of the childcare. What find in our department is that men and women take often equal responsibility in leaving at a certain time to pick up a child and then of course you know that they're going to be working at home until midnight. So, if you make a supportive environment where people can be flexible, they will thank you by doing great research in the spare time that they have available.

Interviewer - Meera Senthilingham

So, is anything actually happening at the moment to address it?

Interviewee - Polly Arnold

University departments and universities themselves are all being encouraged to apply for the Athena Swan awards which recognize the commitment not just to advancing women's careers in STEM but also to making a work place where everybody can thrive. We recognized that measures that you put in place that would look after and encourage women are good for everybody. So, we were awarded the Athena Swan gold award. We were the second department to get this in the UK and there's a suggestion that the award of this might be linked to your ability to attract funding from the research councils in the future which I think is a really positive step.

Interviewer - Meera Senthilingham

Polly Arnold, Professor of Chemistry at the University of Edinburgh.

(28:46 - Chemists welcome newest member of nanocarbon family)

Interviewer - Meera Senthilingham

Now, a new group of molecules, resembling a pringle, a nanopringle. Pat?

Interviewee - Patrick Walter

Yes, some researchers in Japan have created a whole new family of nanocarbons. These researchers have been working on nanocarbons for a little while making small planar nanographene. These are flat structures, but now they have come up with what is basically a graphene pringle, if you like.

Interviewer - Meera Senthilingham

So, what is a graphene pringle and how have they made it?

Interviewee - Patrick Walter

Well, it comes down to graphene I suppose. So, graphene is an allotrope of carbon.  So, it’s just made of carbon atoms and it took the 2010 Nobel Prize for Konstantin Novoselov and Andre Geim at the University of Manchester and what they did was they isolated graphene for the first time. So, graphene, it’s easy to think of graphene as like chicken wire, so lots of hexagons of carbon all joined together into a big flat structure that's only one atom thick. And the great thing about graphene is it has all sorts of exciting interesting electrical properties, electronic properties. So it’s a very good conductor, so people have started to use it in things like sensors, there's talk of using it as a replacement for silicon. But these guys are investigating very small little slivers of graphene, only 26 rings of carbon in size.

Interviewer - Meera Senthilingham

So, who's actually been working on this new structure?

Interviewee - Patrick Walter

So, it’s Kenichiro Itami's team at Nagoya University in Japan. He's done quite a bit of work on nanographenes before, actually synthesizing them from the bottom up. So these are small 26 member rings that he's made from bottom up creating them from nothing, pretty much.  And what he's done here instead is he started with corannulene. So corannulene is kind of like a graphene bowl almost. So, it’s a five membered ring and then it’s surrounded by six membered rings all linked up. So, you have this small slightly warped bowl. There's a bit of CH activation going on to add the next five rings of carbon onto this bowl. So this is a palladium catalyzed reaction that added the next five, just six-membered rings to the bowl and then using cyclodehydrogenation processes, they were able to link up, to cyclise all these five new rings that were added to the bowl.

So what you have is the bowl, then you have five six-membered rings dotted around the bowl attached to it, then you're linking up these five rings to create heptagons, seven-membered rings lying between each of these six-membered rings. Think of it as adding another layer to the bowl. But in this case, because you've got these seven-membered rings you're kind of flipping it out, so, the bowl is kind of going up and the edges are turning down. So this is where you can think of it like a graphene pringle.

So, what can you do with these kinds of things? That's still a little unclear at the moment. But they did do a bit of work on the properties of the nanographenes - of these graphene pringles - and they do have some slightly different electronic properties. They absorb more broadly in the visible spectra, than planar, flat nanographenes do and they're also soluble in common organic solvents like dichloromethane which planar nanographenes aren't at all, they're completely insoluble. So, there's some interesting things going on there, but this is still really very preliminary stuff.

(32:24 - Spectral library chronicles chemical evolution of Italian stamps)

Interviewer - Meera Senthilingham

Thanks Pat and so moving from small bits of carbon to small pieces of paper, and stamps specifically Phil…

Interviewee - Phil Robinson

That's right. Stamp collectors, well Italian stamp collectors who will be celebrating the work of some Italian scientists who've done a comprehensive analysis of 150 years of Italian stamps to create a database of the materials and production, and therefore the production methods, of the entire period of Italian postal history.

Interviewer - Meera Senthilingham

What kind of analysis have they done?

Interviewee - Phil Robinson

So, the analysis done is a spectroscopic analysis using infrared spectroscopy. So, very simply that's if you shine infrared light onto a sample, the components of that sample will absorb certain frequencies of that light and those are characteristic of those components of a sample. So, they conducted this analysis, this IR spectroscopy, on over a 180 individual stamps that covered this 150-year period, revealing the different materials that were part of the stamp, the paper, the inks and the adhesives and so on.

Interviewer - Meera Senthilingham

So, who has been working on this and what are some of the uses of having this level of information about them?

Interviewee - Phil Robinson

Okay, well the work was carried out by Ludovico Valli at the University of Salento in Italy. So it’s useful from the point of view of cultural heritage obviously, but it’s also been used, and in fact as part of this research was used, to identify forgeries, fakes.  If you can identify the components of authentic samples, then you can look at any other examples that are claiming to be authentic and determine whether or not that’s true. So in this case, they identified that a sample of the Gronchi Rosa stamp, now this was a very rare stamp. Rosa is a pink coloured stamp that enjoyed a very short run because on the stamp the border of one of the other countries - Peru I think - is incorrect. This was noticed very quickly and the stamps were withdrawn and a new one issued, but not before some collectors had managed to get their hands on those samples. And as part of this research Ludovico Valli and his team identified that a particular Gronchi Rosa example was in fact fake, it didn't contain the kaolin component of the ink in the authentic sample.

Interviewer - Meera Senthilingham

I guess the owner of that wasn't very happy.

Interviewee - Phil Robinson

I guess not, no. They don't mention where that particular sample came from, but if it was in a private collection, I think, they might be keeping quiet about it, I suppose.

Interviewer - Meera Senthilingham

What other information could be added to this database and how?

Interviewee - Phil Robinson

Well other spectroscopic techniques could be applied to stamps to make the database comprehensive. IR will tell you a lot of information but it doesn't tell you everything and so some of the components that are in the stamps, we need to use other spectroscopic techniques to identify those and that is what Ludovico intends to do next, to make that database truly comprehensive.

Interviewer - Meera Senthilingham

Thank you Phil and also now it’s time for this month's trivia and we're celebrating an anniversary of sorts.

Interviewee - Phil Robinson

That's right. So, this day well on the 31st of August on 1909 syphilitic rabbits were celebrating.

Interviewer - Meera Senthilingham

Why was that?

Interviewee - Phil Robinson

Why, indeed you might ask! Well, because they didn't have syphilis anymore. Thanks to the work of Paul Ehrlich and his discovery of the anti-syphilitic drug, Salvarsan, the first chemotherapeutic drug actually that went onto be the premier treatment for syphilis all around the world, became the most prescribed drug in the world at the time in fact.

Interviewer - Meera Senthilingham

And so the rabbits were celebrating because they were the first models for it?

Interviewee - Phil Robinson

Exactly. So, after trying out on the rabbits it quickly made its way to humans and the rest is history.

Interviewer - Meera Senthilingham

A syphilis-free history and you can hear more about Salvarsan by listening to the Chemistry in its Element podcast on the Chemistry World website. Thank you Phil and the rest of the Chemistry World team this month, Patrick Walter and Neil Withers as well as our guests, Emma Smith and Polly Arnold. I'm Meera Senthilingham from thenakedscientists.com. The Chemistry World podcast is sponsored by Waters, World Leaders in Innovative Analytical Science Solutions.

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