Naked Science Question and Answer and the World of Chemistry

This week Chris, Dave and Kat explain where the sand in the Sahara comes from, if mirrors can reflect x-rays, if it is dangerous to live near a phone mast, and whether splitting...
14 January 2007
Presented by Chris Smith, Dave Ansell, Kat Arney


With a new year comes a whole new stack of science questions to challenge Dr Chris, Dr Dave and Dr Kat. This week they explain where the sand in the Sahara comes from, whether mirrors can reflect x-rays, if it is dangerous to live near a phone mast, and whether splitting water could solve our energy problems. We are also joined by the editor of Chemistry World, Dr Mark Peplow, who talks about labs the size of a postage stamp, nanoparticles in exhaust fumes, and how putting milk in your tea might not be such a good idea, and sticking with chemistry, Dave Ansell discovers which household liquids make dirty pennies look like new. In the fourth part of our series on science and colour, Anna Lacey finds out how wearing red could turn you into a world-class sportsperson.

In this episode

Alzheimer's Gene Tracked Down

A collaboration of scientists from the US, Canada, Europe and Asia have discovered a new gene that could be important in Alzheimer's disease... and hopefully they can remember where they put it. The researchers think that faults in a gene called SORL1 might help with the formation of clumps of protein in the brain, known as amyloid plaques. These plaques are a classic hallmark of Alzheimer's, so the researchers started to look at genes that are involved in processing amyloid proteins. To find the gene, the scientists combed through genetic data taken from many families where more than one person had Alzheimer's. They found that many of the people from the families had faults in SORL1, but not in six other genes that are thought to be involved in amyloid processing. To confirm the finding, they studied information from a wide range of families across the globe, and found the same mistakes in SORL1. The team also measured the levels of SORL1 protein in the blood of Alzheimer's sufferers. They found less than half the level of SORL1 in patients compared to unaffected people. And in lab experiments the researchers noticed that cells with low levels of SORL1 couldn't shift amyloid proteins around properly, which might suggest a way to explain the build-up of plaques in Alzheimer's patients with the faulty gene. So far, the team have found 29 different variations in the gene, in a region that's commonly faulty in the disease. At the moment they haven't mapped any of these specifically to Alzheimer's, but that will be the next stage of the project. They also want to find out if any other factors can influence the levels of SORL1, and how the different versions of SORL1 might contribute to the development of amyloid plaques.

- The World of Chemistry

Labs on a chip and milk in tea,

The World of Chemistry
with Dr Mark Peplow, editor of Chemistry World

Chris - Joining us now from Chemistry World is Mark Peplow. Welcome to the Naked Scientists. You gave us a rundown on why Alexander Litvinenko had a bit of a horrid time when you joined us in December. This month there's some very exciting news, so let's start at the top of the list: how researchers are using heart cells to pump things around labs on chips. Perhaps you'd better start off by describing what a lab on a chip is.

Mark - Chemists are very interested in trying to shrink their laboratories down until they're the size of the sort of chip you get in your computer; maybe just the size of a postage stamp. Now these can be used for chemical reactions on very small scales. Similar sorts of technologies could be used in medical implants as well and this particular breakthrough, which has come from some Japanese scientists, is that rather than using a battery-powered pump to move liquids around, they've actually managed to strap a couple of bundles of heart cells on either side of a plastic ball. Those heart cells will stay alive as long as you keep feeding them nutrients for up to five days actually. And they actually pump continuously as long as you keep them bathed in nutrients and actually pump fluids through this little ball of plastic. It's only about five millimetres wide, but it's a really nice proof of principle that you don't necessarily need batteries on these tiny pumps.

Chris - Is it actually worth doing though? Why not have tiny pumps? Why use heart cells? It sounds fiddly.

Mark - If you're actually constructing this on a lab, one of the difficulties could be that while technology in terms of moving liquids around and doing chemical reactions - that's shrinking all the time. Battery technology is developing quite a lot slower, so there's no point in having a tiny laboratory is you have to have a massive battery to power it inside. In a sense, the same is true if you're using medical implants. Batteries can only last so long so one can imagine that in the future if you can actually attach heart cells to a pump so it's actually going to work continuously, all you need to do is to keep feeding them nutrients and they will go on and on and on. So they could even beat Ever Ready batteries!

Kat - It is one of the most crazy things I've ever seen in science looking down a microscope at a petri dish full of cells and seeing them beating, because they were heart cells growing in the lab. So what's the deal with nanoparticles in exhaust fumes? Are nanoparticles dangerous? What's all that about?

Mark - If you look hard enough, you can find them pretty much anywhere. Nanoparticles are basically anything that you can measure in billionths of a metre, so they're maybe a thousand times smaller than the width of a human hair, something like that. We already know quite a lot about microparticles in exhaust; you can find them in diesel emissions and things like that. Now they're just about one fifth of the width of a hair, so we're talking about a completely different scale. So Justin Linguard and some of his colleagues at the University of Leeds have basically sat out on a roadside for a couple of months in Leeds and just sucked up particles from the air to find out what's in there. Interestingly they find that if you just count the number of particles, the vast majority, about 90% of them, are these nanoparticles. Although we don't know exactly what risks are associated with these, there's some suspicion that if you inhale them, they can potentially get into the lungs through tiny alveoli and through the walls because they're so small. They could then go into your blood stream. Again, we don't know what the effects of these might be once they're there, but one might suspect that it's not going to be ideal.

Dave - So what's this about milk and tea and it not being very helpful?

Mark - It's been around in the news quite a bit for the last week or two actually. Many people drink tea because of its antioxidant properties and it's stuffed full of these things called polyphenyls, which are supposed to have good effects for you. But some German researchers have found that if you add milk to your tea, it actually neutralises those health benefits. They suspect that what's going on is that once you put milk in, proteins called caseins actually wrap themselves round these beneficial polyphenyls that are good for helping your arteries expand and increasing your blood flow, and stop them from working in your blood stream. So effectively, if you put milk in your tea, it's no better for you than drinking hot water.

Kat - It's certainly interesting because that was a laboratory chemical study, but some of the studies done in huge populations of people have found beneficial effects of tea and green tea in things like cancer and heart disease, so it'll be interesting to kind of drill down into it.

Mark - One of the interesting things that our reporters found on the Chemistry World team was that when they spoke to some researchers in the States about this, they pointed out that yes, many studies had found benefits to drinking green and black tea in countries in Asia and things like that. But when you actually look at the UK and the epidemiology, there's no benefit from tea drinking at all even though we're a nation of tea drinkers.

Chris - I think we drink more tea than anyone else per capita.

Mark - Yeah, and the reason we don't get any benefit from that is maybe that we unusually choose to drink our tea with milk.

- The Science of Colour 4

How wearing red could make you a top sportsman

The Science of Colour 4
with Anna Lacey

Chris - Time for another instalment of our science and colour series. This week, our Naked Scientist Anna Lacey is looking at how the colour red could turn you into a world-class sportsman.

Anna - Here's a question for you. What's the most important thing to think about if you're an Olympic wrestler, a Premiership footballer, or a seasoned athlete like myself? Is it training hard? Eating the right things? Well maybe, but it turns out that the colour of your sports kit may make the difference between winning and losing. To explain why while I do some stretches, here's Dr Russell Hill from the Evolutionary Anthropology group at Durham University.

Russell - We looked at the results from the combat competitions at the recent Olympic Games to see if colour was influencing the success of competitors within events such as boxing and wrestling. And what we found was that even though individuals were randomly assigned either red or blue to wear, there were significantly more winners actually wearing the red colouration.

Anna - So why do you think this might be?

Russell - Well we know that within the animal kingdom, the colour red is frequently associated with dominance. For example, in mandrill monkeys it's only the dominant males that are able to display this red colouration as a sort of badge of status. And we know that it's linked to testosterone levels in these males, so we think that something similar might be happening in human contests and that by wearing this red stimulus, it's giving competitors some form of advantage in one-on-one contests.

Anna - So do you think that this wearing red is going to have any bearing on whether someone like, say, Manchester United wins the league versus Chelsea?

Russell - It's certainly true that if you look back over the last few decades that teams wearing red have dominated the football leagues; both Liverpool, Arsenal and Manchester United all wear red as their primary shirt colour. What is important though is that individuals or teams need to be closely matched before this red advantage takes effect. Simply wearing red doesn't make you a brilliant footballer or boxer. It is possible for teams such as Chelsea to overcome that by spending an awful lot of money. So Manchester United do have an advantage as long as it remains a relatively close competition, but if they go out and spend those Russian millions again this January, Chelsea could find themselves way out in front again.

Anna - I mean there are a lot of other things that are associated with the colour red: not only aggression, but anger, passion, even warmth. Why do you think that red is so important in these kinds of contexts?

Russell - We're not entirely sure. We know that it's a consistent signal throughout animals, so the fact that it's important in humans is perhaps not surprising. Red is often one of the first colours that tends to get identified after black and white or dark and light within human societies. So it clearly is an important colour and that may be due to the way it's linked in with the colour of blood.

Anna - The associations we make, such as red representing blood and anger, and blue as tranquil and cold, are heard pretty much everywhere. But the colours and what they relate to are not the same the world over. From the Department of Social Anthropology at Cambridge University, here's Professor Alan MacFarlane.

Alan - A very famous difference is that in the West, black is the colour of death and evil and things like this, whereas in China, Japan and East Asia, white is the colour of death. So there's a complete opposition.

Anna - Is it the case that now the world is becoming much smaller, are the colour associations changing do you think?

Alan - I think they are. That's to say for instance that a Japanese or Chinese wedding will have white, I mean the bride will wear white, because it's a part of becoming modern and Western et cetera, to adopt the colour categories of whatever is the leading power in the world. So I think there is a great homogenisation going on all over the world.

Anna - Even if everyone ends up describing emotions and using colour in the same way, something that many would see as a great shame, we can at least breathe a sigh of relief when we look at the huge variety of colour in nature. So join me next week for the final part of the series and a whistle stop tour of colour in the animal kingdom.


- Soundproof stethoscope

The Naked Scientists spoke to Chelsea Wald and Bob Hirshon, AAAS, the Science Society

Soundproof stethoscope
with Chelsea Wald and Bob Hirshon, AAAS, the Science Society

Chelsea - There's no instrument more central to a doctor's toolkit than a stethoscope. That's why scientists at the Army Aeromedical Research Lab have designed a new kind that works in noisy conditions, like on a battlefield, in a helicopter, or in a stadium. Acoustical engineer Adrian Houtsma says it uses ultrasound-sound waves at a frequency of about two and a half million hertz. The human ear can only hear up to about twenty thousand hertz.

Adrian - And we realized that a helicopter may make a lot of noise, but there is no noise at 2.5 megahertz, so the two will not interfere with each other.

Chelsea - He says instead of listening passively to the heartbeat, the ultrasound stethoscope sends high-frequency sound waves into the tissue, listens as they bounce back, and then transforms them into sound the doctor can hear.

Adrain - It looks and sounds very similar to a regular conventional stethoscope, but internally it is something totally different. And if you listen carefully it sounds a little different.

Chelsea - In fact, he thinks more studies may reveal that the ultrasound stethoscope can hear details that conventional stethoscopes can't, like damage in a specific valve. That could make doctors look at this classic tool of medicine in a whole new light.

Bob - Thanks, Chelsea. If you ask your kids to turn down the volume on the TV while paying your bills, be careful: you might make more mistakes if you can barely hear it at all. This according to Boston University psychologist Takeo Watanabe and his colleagues. They asked volunteers to work on a simple computer task, while distracting dots darted around on the screen. And the volunteers performed worst when the distractions were too small to consciously notice. Brain imaging studies showed that these subliminal distractions mostly bypassed the prefrontal cortex, which filters out irrelevant information, and went straight to the brain's visual centers.

Takeo - As a result, the motion was processed, and resulted in disrupting the task performance more greatly.

Bob - So muting distractions without eliminating them may actually hurt productivity.

Chelsea - Thanks, Bob. Next time we'll be back to distract you with more science news from the States. Until then, I'm Chelsea Wald.

Bob - And I'm Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists.

- Where does desert sand come from?

Where does all the sand in the Sahara desert come from?

Where does desert sand come from?

Sand is tiny fragments of rock. When rock wears down you get smaller bits of rock, or pebbles, and when they wear down you get even smaller bits and eventually you get down to sand, or silica. The reason it ends up washing up on the beach is that the sea or wind can move sand around very easily while rocks are more likely to stay put. This separates things by size, and the sand ends up on the beach and the rocks end up on the seabed. There were lots of sand stones in the Sahara which have weathered and broken down over time from rain, and sun and wind. This has produced accumulations of sand which have built up over time to produce this massive desert. Rocks are made up of lots of different things other than silica, or quartz. But the silica is the toughest material which is why it gets left over after a lots of weathering, when everything else has dissolved or turned to dust.

- Can you reflect x-rays or radio waves?

Mirrors reflect visible light. But how effective are they at reflecting other electromagnetic waves like x-rays and radio waves?

Can you reflect x-rays or radio waves?

It depends what you make the mirror out of. If you're looking at radio waves then the mirror will have to be made of thicker metal, because as you increase the wavelength you also have to increase the thickness of the metal to get the same reflectivity. That's actually how satellite dishes work. They're basically a big curved mirror that concentrates all of the microwaves coming down from the satellite. They're often full of holes to keep the weight down, and this doesn't matter because the wavelength of the waves is larger than the holes. This is the same principle as seeing a light on in your microwave. You can see the light escaping through the door but the microwaves aren't escaping because they're too long. Once you get beyond visible light into the shorter wavelengths; ultraviolet light is easy to make mirrors for, but x-rays are very difficult. And so making x-ray telescopes is very difficult. Sometimes they do it by using a bag of gas to act like a lens rather than mirrors or by using a metal mirror but at a very grazing angle which makes the mirror very large. Mobile phone waves are at the microwave end of radio waves, and a sheet of aluminium would work nicely as a mirror for those.

- How do air sacs in the lungs work?

How do air sacs in the lungs help with gas exchange?

How do air sacs in the lungs work?

Your lungs are not just like balloons. They are filled with millions of tiny air spaces called alveoli, which are the air sacs you mentioned. The reason the lungs don't just have one big balloon, but instead contain millions of tiny balloons, is that each balloon has to have a wall. In the wall of each balloon are tiny capillaries, which are very thin-walled blood vessels. The blood from your heart gets pumped through your lungs, around the walls of these tiny air sacs first, and then back to the heart before it gets jetted off around the rest of the body. As the blood flows through these tiny blood vessels around the air sacs or alveoli, it exchanges carbon dioxide, which is dissolved in the blood, which gets chucked out of the blood because there's more in the blood than there is in the air sac. And oxygen, which there's lots of in the air sac, comes out of the alveolus and into the blood. It forms a compound with the haemoglobin which is the stuff that makes your blood red, and gets carried away. The average red blood cell takes about 0.3 seconds to pick up all the oxygen it can from the wall of the alviolus but it spends 0.8 seconds actually making that journey. So the red blood cell has nearly three times the time it needs to pick up all the gas it needs. So that's how the gas exchange occurs and why you don't just have one balloon in your chest but millions of tiny balloons. It gives your lungs the surface area of about a tennis court if you were to spread them all out. And this means that there is a large surface area of lung tissue and blood vessels in contact with the gases to enable efficient gas exchange.

- Can we split water?

Can we crack water into it's components of oxygen and hydrogen and then burn the hydrogen using the oxygen to create a process to turn wa...

Can we split water?

Unfortunately it takes the same energy or more to split the water into hydrogen and oxygen than you could possibly get by burning the two back together again. So it will just cost you energy and not get you anywhere. There's no such thing as a free lunch in the world of physics! However, there are some fuel cells that use the energy from light to split the hydrogen and oxygen in water, and you can then use that to get power.

- Are mobile phone masts dangerous?

Is it dangerous to live 500 metres away from a mobile phone mast?

Are mobile phone masts dangerous?

It's far less dangerous than using the phone yourself. No one's actually found a dangerous relationship with using a phone. When you use a phone, that transmitter is a couple of centimetres away from your head, and the strength of the signal goes down with the distance squared. So it's going to be thousands and thousands of times weaker than your mobile phone right next to your head. To explore the science of this - if you look at the energy of a microwave, and the reason we have these things in our kitchen and cook with them and we are happy to put a microwave source or a mobile phone to the side of our heads, is because the energy in the wave of a microwave is not sufficient to break chemical bonds in the same way that an x-ray or a gamma ray, or more intense forms can. And therefore they're viewed as non-ionising forms of radioation, and are viewed to be safe. That said, there's no evidence that if you do expose your nervous system to these things that they won't have a temperature effect; because we think that they might warm your head up a little bit if you're exposed to a phone. But of course the mast is much further away than a phone is. But also, exposing tissue to microwaves for long periods of time may or may not have some sort of growth related effect. Certainly in terms of cancer there isn't enough energy in phone radiation to damage DNA which is the ultimate cause of cancer. Virtually all the studies that have been done have not found a significant link between mobile phone use and cancer. The one thing we don't have is really long term data and that's hopefully coming in in the next couple of years. But the studies certainly haven't found an effect in terms of cancer.

- Why are there fossils in some rocks but not others?

The Hunstanton cliffs are made up of layers of white chalk, red chalk and the main part is sandstone at the base. Why are there fossils i...

Why are there fossils in some rocks but not others?

The sandstone was probably produced in the permian period when the country was basically a big desert. And then the rocks probably all dropped a few metres and was under water, which is when the chalk was deposited by little things under the sea. And then it's all been lifted up again to make the cliffs you know at the moment.

- Is there a reason for cyclic weight loss?

Is there a reason for cyclic weight loss?

Is there a reason for cyclic weight loss?

When people begin to diet and lose weight they lose enormous amounts of weight in the first few weeks, and then their progress slows. The reason for that is that the body initially burns off things called glycogens. That's a polymer of sugar, and it binds enormous amounts of water. Which means that when you burn that off and use it for energy, you lose the water from the body as urine. So you lose double the amount of weight - sugar weight plus water weight. Then you start to burn fat and of course fat doesn't mix with water. So the weight loss slows down. Every so often if you have a bit of a binge, or it's Christmas or whatever, and you pack in some carbohydrates, they tend to turn into a bit of glycogen and your weight creeps up a tiny bit. Then you go back on your severe diet and carry on burning fat and the first thing your body does is to say I'm getting hungry, I'm going to burn that bit of glycogen. So it does that, you lose the water again and you're back to how you were when you were just burning fat.

- How does my body absorb the morphine form a patch?

How does my body absorb the morphine in my dry-feeling patch?

How does my body absorb the morphine form a patch?

Morphine gets into the brain and gives pain relief very effectively because it's very very soluble in fat. When you stick one of these patches on the body, the morphine is in a special reservior in the patch and it slowly comes through a membrane, and dissolves in the fat that's in your skin and your body and gets into the blood stream. And that's how you absorb it.


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