October 2009

Chemistry World Podcast - October 2009

00.11- Introduction 

02.02 -Sniffing out the chemical profile of death 

04.42 - Are antioxidants always good for you? 

07.53 - James Galloway on concerns that humans are upsetting the nitrogen cycle 

14.55 - Is nitrous oxide now the biggest threat to the ozone layer? 

17.45 - Plugging in to paper batteries 

20.22 - Grab the garlic - Jeya Henry shares his tips on the top three health-giving spices 

27.09 - The new bond found to hold collagen together 

30.20 - Making MOFs more active 

32.50 - The chemical conundrum - what did L-cysteine, used in bread making, used to be made from? 

(Promo)

Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.

(End Promo)

(00.11 - Introduction)

Interviewer - Meera Senthilingam

Welcome to the October edition of the Chemistry World Podcast with James Mitchell Crow, Phillip Broadwith, Bibiana Campos-Seijo, and Tom Bond.  I'm Meera Senthilingam from thenakedscientists dot com. In this month's show, we explore some deadly scents.

Interviewee - Bibiana Campos-Seijo

They want to create a chemical profile for this, so that they can ultimately design a device that can be carried to the pesticides to discover bodies and then identify how long they have been dead for. 

Interviewer - Meera Senthilingam

Sniffing out the crime scene. Bibi Campos-Seijo will be explaining how researchers have identified the scents of death as well as how this will make crime scene investigations more efficient. Also on the way, it may give you smelly breath, but garlic is the godfather of the spices.

Interviewee - Jeya Henry 

Garlic contains a group of thiocyanates and it turns out that it has got multifaceted attributes. It certainly is also antibacteriocide, reduces the cholesterol, improves your digestion, the anti-cancer agent, the lists are infinite in terms of its potential.

Interviewer - Meera Senthilingam

Jeya Henry will be revealing the health benefits of his top three spices as well as garlic, shortly. We've also got a new greener design for batteries.

Interviewee - James Mitchell Crow

Well, these are metal-free rechargeable batteries and as you say they are made largely from paper and the advantage that they have over current batteries is that they can be made extremely thin and they can also be made flexible.   

Interviewer - Meera Senthilingam

James Mitchell Crow will be explaining just how this paper-thin battery will work later in the show. That's all coming up on this month's 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)

(02.02 -Sniffing out the chemical profile of death) 

Interviewer - Meera Senthilingam

Now first this month, we imagine going out to a crime scene. A body has been found, but no one knows how long it's been there. Currently it's difficult to work this out, whilst out on location, but now it may be slightly easier. Thanks to a new device that could sniff out the different stages of decomposition. Does this really work, Bibi?

Interviewee - Bibiana Campos-Seijo 

Yes, it happens that dogs that are searching for human remains in disaster sites might be soon out of a job because a couple of researchers at Pennsylvania State University are trying to identify the chemical composition of death. They basically have used pigs because pigs replicate the five stages of decomposition of bodies that the humans go through. Basically, they euthanized the pigs and then they tried to collect the volatile organic compounds that are released during the early stages of decomposition. They want to create a chemical profile for death, so that they can ultimately design a device that can be carried to the pesticides or whatever and then help to discover bodies and then identify how long they have been dead for.

Interviewer - Meera Senthilingam

So, what materials where they using to collect the volatile organic compounds?

Interviewee - Bibiana Campos-Seijo 

They are using solid-phase microextraction fibres. They have three different types of fibres with polymer coatings on the outside and these are placed over the carcass of the pig within a wooden enclosure that allows airflow I should say that and then these fibres, they are taken regularly back to the lab on ice to avoid the loss of any volatile compounds and then the analysis it directly to a GC-MS apparatus and they have so far worked on the first two weeks from the death of the pig and they have created quick chemical profiles and using these three different types of fibres, they have demonstrated that the chemical profile is virtually identical and is quite accurate in that they see, you know, the same chemicals appear in every time within the same concentration. Other techniques are a lot more complicated, in that they require different type of equipment that needs to have vacuum or some sort of pumping system to draw the air through the collection material. They are going for some, sort of a crime scene investigation sort of device that they can carry and do the analysis in-situ. So hopefully should all be pretty straightforward and ready soon. 

(04.42 - Are antioxidants always good for you?) 

Interviewer - Meera Senthilingam

And well from rotting flesh now over to cancerous cells, Phil. As it seems antioxidants aren't quite as beneficial as we all think.

Interviewee - Phillip Broadwith

Well, yes. There's a lot of discussion about whether antioxidants prevent cancer or perhaps may be at certain stages aren't so useful and what Joan Brugge of Harvard has been looking at is the very early stages of cancer. Now normal cells have to be attached to a sort of scaffolding matrix that provides them with certain nutrients as signalling compounds and as cancer cells divide very quickly, they soon run out of room to be attached to the matrix. So if you think of a cancer tumour, those cells in the middle of that aren't going to be attached to that matrix, so they need to develop a way of surviving away from that.

Interviewer - Meera Senthilingam

The fact that they do this, has the body come up with various ways to attack them and kill them. 

Interviewee - Phillip Broadwith

Yes. Well, there are two different major defence mechanisms. They first is programmed cell death or apoptosis, but a lot of cancers has evolved ways of turning that process off and the second process is that reactive oxygen species which are very oxidizing and help to break down lots of the proteins and molecules in the cell, which cause it to die. 

Interviewer - Meera Senthilingam

So how do the cancerous cells then overcome these natural defence mechanisms? 

Interviewee - Phillip Broadwith

Well, there are two problems. The first is this genetic apoptosis, which they quite happily turned off using various genes. The second is getting energy, one of the main things that being attached to the matrix is it allow them to transport glucose as a source of energy into the cells. If you are not attached to the matrix, that glucose transport mechanism is turned off. So they either need to find another way of getting glucose, which can be done using various genes or they need to find a different source of energy and that different source of energy could be the oxidation of fatty acids.

Interviewer - Meera Senthilingam

So how would they obtain this energy from fatty acids?

Interviewee - Phillip Broadwith

That's where the antioxidants come in. There is a problem with fatty acid oxidation in these cells that have been detached. When the cells are detached, they start producing reactive oxygen species as the secondary defence mechanism to try and kill the cell. That also blocks fatty acid oxidation. If you then add antioxidants into that, you can neutralize the reactive oxygen species and allow the cell to get its energy from fatty acid oxidation.

Interviewer - Meera Senthilingam

So, basically the presence of antioxidants at this early stage of tumour formation is allowing the cells to proliferate because it's allowing them to get energy from the fatty acid metabolism.

Interviewee - Phillip Broadwith

Yes. That's exactly right. 

Interviewer - Meera Senthilingam

So now knowing this, what can be done to understand more about tumour formation and hopefully prevent tumour spread?

Interviewee - Phillip Broadwith

It's crucial that we understand how the metabolism and chemistry that's going on within cancer cells changes through their lifetime. We know that established cancer cells don't use fatty acids as a form of energy because they spend a lot of energy making fatty acids, fatty acids accumulating cancer cells. But it seems that in this very early stage, just when the cells detach from the scaffolding around them that they are using this as a sort of interim source of energy. Understanding that will hopefully help us understand where we can intervene in that process and stop the cancer from spreading.

Interviewer - Meera Senthilingam

So understanding this use of antioxidants in the early stages of cancer cell proliferation could help stop the cancer in its tracks. Thanks Phil.

(07.53 - James Galloway on concerns that humans are upsetting the nitrogen cycle) 

Interviewer - Meera Senthilingam

Now the pollution of our environment and the warming of our planet have been issues that we have been aware of and trying to deal with for a long time now and the main culprit we all seem to be worrying about is carbon dioxide or CO₂, but there's another element that has been causing damage, whilst in the shadows of CO₂and that's nitrogen. James Galloway from the University of Virginia has been trying to bring the trouble nitrogen is causing out into the light, to show that this too is a major environmental concern. 

Interviewee - James Galloway

The current concern regarding nitrogen is that there is too much in the environment. As a background, let me say that nitrogen is very common in the environment, but it's in a form that is not reactive, it's in the form of the molecule N₂, two nitrogen elements put together and that is not biologically reactive mostly, chemically or physically reactive. However, when that N₂is converted to other forms of nitrogen, they become biologically, chemically and physically active. This is a good thing in some sense because all living systems need nitrogen, but because humans are creating these forms of reactive nitrogen at a much faster rate than nature, reactive nitrogen is accumulating in the environment, where it contributes to many, if not most of the environmental impacts that humans and ecosystems are experiencing today. 

Interviewer - Meera Senthilingam

So how does nature create nitrogen in the first place?

Interviewee - James Galloway

Natural systems create reactive nitrogen that is converting inert into any other form of nitrogen, which we term reactive nitrogen by two main processes; the dominant one is biological nitrogen fixation where microorganisms actually within the cells convert N₂into reactive nitrogen. Another important one in some regions is lightening, when lightening occurs, lots of energy is released and the molecule N₂in the atmosphere reacts with oxygen to form nitric oxide. So that's how nature creates reactive nitrogen and nature also converts reactive nitrogen back to N₂in the process of denitrification, so you don't have reactive nitrogen accumulating in the environment. But now humans have come along and by three main mechanisms, they also create reactive nitrogen. First they plant legumes, we think soybeans and peanuts, and by virtue of planting those, these are plants that act as a host for those same bacteria and microorganisms that create reactive nitrogen through biological nitrogen fixation, so they are enhancing nature's ability to create reactive nitrogen. The second one and by far the largest on a global basis, is making of nitrogen fertilizer by the Haber-Bosch process, where under high temperatures and pressures, the molecule N₂and the molecule H₂- hydrogen are reacted to form ammonia. Then the third one is combustion of fossil fuels and you convert N₂in the atmosphere with oxygen over to nitric oxide. 

Interviewer - Meera Senthilingam 

Something that you have come up with, to describe and explain the real kind of problem that nitrogen is having is with your nitrogen cascade. What is this and how does this show the effects of nitrogen and how it's amplified?

Interviewee -James Galloway

The nitrogen cascade is that one atom of nitrogen, one atom of reactive nitrogen created by humans can cascade through the environmental systems, contributing in turn to each of those impacts and so imagine a molecule of nitric acid, a molecule of nitric oxide that is emitted from a car's tailpipe that is emitted into the atmosphere, where it can cause ozone concentrations increase, which contribute to smog, that molecule of nitrogen, that atom of nitrogen can be converted into a particle which can contribute to haze, then that atom of nitrogen can be taken out of the atmosphere by rain and snow, acidifying the rain and snow in the process, which will then acidify soils and streams and lakes and then as this same atom of nitrogen moves through the environmental system is transported in rivers to coastal environment, where it acts as an over enriching nutrient and can cause oxygen loss in coastal environments leading to dead zones and then again the same atom of nitrogen can be converted to a gas called nitrous oxide which is two atoms of nitrogen and one atom of oxygen which would be emitted in the atmosphere as a greenhouse gas, so it contributes to global climate change and then this same atom of nitrogen again in the form of nitrous oxide can diffuse into the stratosphere contributing to stratospheric ozone depletion. And so just this one creation of reactive nitrogen in the form of nitric oxide cascades through all the environmental systems. 

Interviewer - Meera Senthilingam

So what are the proposed solutions, how can we achieve this balance?

Interviewee - James Galloway

The most obvious is since when reactive nitrogen is formed during combustion of fossil fuels that's formed by accident, we don't need that reactive nitrogen. And so we have the technology, we know the science, we have the public policy instruments and in some countries there are laws to decrease the amount of reactive nitrogen emitted to the atmosphere from fossil fuel combustion, so that's simple to do technically. Another way on the food production system is, we can make crops more efficient in taking up reactive nitrogen. Currently, of all the reactive nitrogen in the form nitrogen fertilizer put on crop plants, only about 30 to 50% is taken up by the crop, the rest is lost to the environment. The same can be said about animals, the world consumes a lot of meat, animals need nitrogen just like crops, just like people, so we could make this feeding of animals more efficient, we can have a better mixture of amino acids in the animal feed, so that more of the nitrogen that enters the animal's mouth, stays with the animal, instead of coming out the other end.

Interviewer - Meera Senthilingam

So those are some possible solutions to ease the problem, but as individuals we can play our part too by eating less meat and reducing our fossil fuel consumption. That was James Galloway from the University of Virginia, explaining how the increasing levels of reactive nitrogen in our atmosphere is damaging our environment.

(Promo)

(End Promo)

Interviewer - Meera Senthilingam 

You are listening to the Chemistry World Podcast with me Meera Senthilingam. And still to come, we discover the benefits of spicing up your life, reveal a new, greener form of battery and discover a new chemical bond that could not only help treat Goodpasture's syndrome, but also give us an insight into the entire animal kingdom.

(14.55 - Is nitrous oxide now the biggest threat to the ozone layer?) 

Interviewer - Meera Senthilingam 

But first keeping on the topic of nitrogen, Tom, you found out about another way this element is affecting our atmosphere.

Interviewee -Tom Bond

Yeah that's right. This is a study that has been undertaken by A. R. Ravishankara and his colleagues who are from NOAA, which is the National Oceanic and Atmospheric Administration Research Center, and they are at Colorado in the USA. They've published a study in science, the main point being that nitrous oxide which is N₂O is now thought to be the main contributory factor to the depletion of the ozone layer and it will remain in that status for the rest of this century. 

Interviewer - Meera Senthilingam 

Why is nitrous oxide now the concern and how has it kind of overtaken other potential worries about chemicals that affect the ozone? 

Interviewee -Tom Bond

It basically seemed that it's been over looked in the past to some extent and that's because most of the focus has been on the CFCs and also HCFCs. CFCs are chlorofluorocarbons and the HCFCs are the hydrochloroflurocarbons. It was really in the later years of the last century, the 1980s where pictures of the ozone layer showed that there was a big hole there and this kind of raised the issue in the public consciousness and then as a result of that the Montreal Protocol was formulated in 1987. So this banned use of the CFCs which at the time were the most destructive chemicals depleting the ozone layer. The HCFCs were then introduced as temporary replacements for the CFCs. They are also harmful towards the ozone layer, but not as much as the CFCs, but that really is why no one has looked particularly at nitrous oxide. This group has run a computational simulation model which shows that now N₂O is the main chemical depleting the ozone layer. 

Interviewer - Meera Senthilingam

How is this nitrous oxide created by human activity and what effect does it actually have on our ozone, why does it damage our Ozone?

Interviewee - Tom Bond 

They are both natural and manmade sources and I think actually natural sources are still more important than manmade nitrous oxide. So, depends on which information source you look at, but roughly 30% of the nitrous oxide, which ends up in the stratosphere comes from manmade sources. Of this the largest single source is nitrate fertilizers used for agriculture and then it ends up as nitrogen oxides in the atmosphere and then these nitrogen oxides react with ozone thus depleting it.

Interviewer - Meera Senthilingam

Just how big a problem is nitrous oxide? So what levels are we looking at here, in our atmosphere? 

Interviewee - Tom Bond

What they've done, they have calculated something called the ODP which is the ozone depleting potential. Nitrous oxide has a similar ODP to some of the HCFCs.

(17.45 - Plugging in to paper batteries) 

Interviewer - Meera Senthilingam 

Okay, so everyone needs to do their bit to help the environment as well and one way we could do this in the future is by using paper batteries. So, what are these about, James?

Interviewee - James Mitchell Crow

Well, these are metal-free rechargeable batteries and as you say they are made largely from paper and the advantage that they have over current batteries is that they can be made extremely thin and they can also be made flexible, so you could even consider rolling them up to increase the density of the power that they can hold. This is some research that's come out of Uppsala University in Sweden and has basically two research groups that were working on quite different standing things. One group were looking at conducting organic polymers, so these are long chain organic molecules, which have lots of double bonds in so they can conduct electrons along the backbone of the molecule and the other group were looking at cellulose produced by a particular kind of algae and this cellulose has acquired unique nano structure has an extremely high surface area, extremely rough surface on the nanoscale. So what these groups have done is get together and basically coat the cellulose with this conducing polymer and they found that makes a really effective electrode. That's what they have done a little while ago. What they've done now is put two of those electrodes together, separated by a sheet of filter paper that has just been soaked in some salty water and discovered that that works as quite an effective battery.

Interviewer - Meera Senthilingam

Although it may work as a battery, just what kind of figures are we looking at into the actual voltage and the power that these batteries create?

Interviewee - James Mitchell Crow

In terms of the capacity, it's quite a lot lower than the lithium ion batteries that we all have in our laptops and mobile phones these days. I think they've done a thousand cycles of charging and discharging and shown that they do have quite a long life. They work in quite a similar way to lithium ion batteries, but it's the chloride ions from the salty water that actually transfers from one electrode to the other, so they flow in one direction when it's discharging and then sort of pump back the other way, when the batteries are being charged up.

Interviewer - Meera Senthilingam

So due to this flexibility and their thinness what are the potential uses then of these batteries?

Interviewee - James Mitchell Crow

Well, they are also quite lightweight as well as you can imagine incorporating them into clothing to power all sorts of devices, the authors are even suggesting they could be impregnated into wallpaper to power, I don't know, goodness knows what, your wall clock or something and they've also talked about putting them into packaging, powering active displays on things like medicines, for example, could be quite beneficial.

Interviewer - Meera Senthilingam

So we could soon see models with lights flashing all down them as they walk down the catwalk and have light designs covering our walls. Thanks James.

(20.22 - Grab the garlic - Jeya Henry shares his tips on the top three health-giving spices) 

Interviewer - Meera Senthilingam

Now spices such as garlic, cinnamon, chilly own acquired taste. There are some of us that put them in everything we cook or boast about how much of things like chilly we can handle in our food and there are others that just can't stand them. But nutritionists have been studying these spices for many years now and have found a variety of benefits of these spices on our health. One such scientist is Jeya Henry from Oxford Brookes University and he has identified his top three spices in terms of their health benefits. So I spoke to him to find out what these spices are and at number three we have cinnamon. 

Interviewee - Jeya Henry

Well, it turns out that cinnamon in recent years has been shown repeatedly from different laboratories that it has a very unique property of modulating your blood glucose and in other words many people around the world are diabetic, which is as you know a way in which your blood glucose levels are not very well controlled, so you have what is called hyperglycaemia and the common intervention is to either provide insulin or some tablets that cause you to reduce your blood glucose. Now it is quite challenging that people have noticed from the time of the Vedic period which goes back as you know millennia, that cinnamon has an effect on what they call at that time, sugar problems, and I think they were quite clever in articulating that, but recent studies both from America and from Europe have shown that yes, providing cinnamon as a powder form in food appears to have a moderating effect on your blood glucose and I think that's a very exciting observation.

Interviewer - Meera Senthilingam

Now what is the actual compound in the cinnamon that has this effect on the body and how does it work? 

Interviewee - Jeya Henry

Well, I think those two questions have still not been resolved, I think the analytical chemistry is still up on speed, but also we do not know whether it actually stimulates insulin production, which is what the speculation has been, as you know, there are compounds that are available in the market, pharmacological, that stimulate insulin production by the pancreas. So therefore it could well be that we are now on a starting of a journey, so at the moment, it's what I would call an observational study, so the next stage will be the analytical chemistry to identify the particular compound.

Interviewer - Meera Senthilingam 

Now then moving up your ranks to number two is turmeric. So what is it about turmeric that's beneficial to the human body?

Interviewee - Jeya Henry

Well, turmeric has been used for centuries, certainly in India, as an excellent antimicrobial and a kind of antiseptic and in India, especially, young women who have just had a bath, they normally have their face garnished with turmeric because it actually gets rid of your pimples