Why am I doing this?

At last the Cheiron School is over. Don't get me wrong it was great fun, met loads of great new people and learned a hell of a lot about X-ray science, but, it was also a massive brain drain, not least because I’ve also been working on the beamline during the nights. Hooray for 4 hours sleep, I’ll be totally out of wack by this Sunday I feel.

But enough of my moaning, I thought I’d spend this post talking a bit more about some of the interesting applications of synchrotron radiation that I’ve learned about over the course of the past week. It really has reminded me what I’m pouring my hours and energy in to.

To bring those who don’t know upto speed, Synchrotrons are giant circular facilities that are constructed to churn out light of high brilliance in the high end o the optical spectrum. What I mean by tha is the light has a ver small wavelength. In general they are in the x-ray region, between 0.8 and 10 nm although they do go higher.

They are produced by the periodic interference of a relativistic electron beam as it passes through large electromagnets, which maintain their curved path around the ring. These magnets can either be large individuals or, more commonly these days, arrays of magnets called undualtors and, yes this really is their name, wigglers.

Whilst synchrotrons used to be firmly in the grasp of high energy physics in recent years their doors have begun to open to all aspects of scientific research, from physical chemistry, materials science, geology and of course very close to my heart, biological and biomedical sciences.

I won’t bore you, or myself to be frank, by running through a list of all the crazy stuff that goes on here but I would like to outline some of the surprising things I’ve heard about. Hopefully after reading you’ll realize the work here is not all just abstract work by grand theorists, some of the applications are very real and close to home.

This is a good thing as these facilities are flipping expensive and horrendously inefficient. In fact the average synchrotron experiment utilizes maybe 1% of the total power output and often even less. This is partly down to the difficulties in alignment since if you want to see small you’ve gotta go big. But that's a story for another time.

So for my first example I’d like to present some work that is helping premature babies to breathe. Whilst being born the contents of a babies lungs have to rapidly switch from a liquid environment to a gaseous one. No one is quite sure how exactly this switch occurs but what we do know is that a lot of the time when babies are born premature, it doesn’t happen.

Now whilst with modern medicine a good proportion of these babies survivee due to assisted ventilation methods, around 30% will develop chronic lung complications in their mid teens. This is an obvious issue and in fact the cause is the assisted ventilation that saves the babies life in the first place, some of the time it will cause the lungs damage that is not fully repaired in the immature infant.

So how can we better understand this process? The answer is X-rays. And when I say X-rays I do actually mean like the radiograms you see get at your local hospital. Sort of. Scientists have found away to utilize the intense brilliance and high coherence of the x-ray sources to take highly detailed snapshots of living tissue.

So how do you do these experiments then? Essentially it is the same as normal radiography, you place the object you want to image in front of the beam and take an exposure. You then measure the change in intensity of the X-rays that come out the other end, due to the different densities of our tissues more or less radiation will be detected.

Of course synchrotron radiation has a very small beam size so you actually have to take multiple thin slices to get a large picture, however due to the much higher peak brilliance (the amount of light photons in a given area) exposure times are much slower.

The other major change is that your detector is a long distance away. By doing this some of the X-rays scattered by the edges of the things they interact with will interfere coherently and increase in intensity. The practical upshot of this is that the resolution at the edges of your image is greatly improved. Whilst thi can happen with normal X-rays it is more pronounced at synchrotrons.

So back to babies. Basically using the techniques described above scientists at spring8 have imaged lungs of premature baby rabbits whilst they breathe. The resolution is such that they can actually see individual alveoli within the lungs. This meant they could quantify the amount of air within the lung at a given time. Incredible.

In doing this they realized something. The rapid filling and emptying of lungs by artificial respirators was causing the lung damage as the lungs never fully filled with air and so water was never fully expelled and the lungs collapsed after each expiration.

They found that by either slowing the rate at which the lungs emptied through a technique know as PEEP (Positive end Respiratory Pressure), or by increasing the length of the first inhalation. the lungs would be fully aerated and would not collapse during expiration. This could really save a lot of lives in the future as it will prevent these fatal lung complications developing in preterm and C-section children.

Example number two of the awesomeness of SR comes this time from a technique known as X-ray fluorescence. This exploits the fact that all elements within the periodic table emit photons (fluorescence) at a given energy following x-ray exposure. Essentially by focusing on a particular energy level you can determine the composition of a material.

More practically, if you are good, this can be used in forensic like the example I’m about to show here. This case dates back to 1998 at a festival in Wakayama, Japan. During it many people grew critically ill and four eventually died. At the time no one knew the cause however after post mortem analysis it was found that they had been poisoned by an Arsenic trioxide laced curry.

The problem lay in the source of the poisoning. It was discovered however, through XRF, that all of the people who had died contained unusual amounts of certain trace elements at a given ratio. By analyzing various samples from the crime seen they manage to discover containers with these elements at the same distinctive ratio.

It was too distinct to be a coincidence and this evidence has been used in the prosecution of the culprits, which even now ongoing due to the circumstantial nature of some of the earlier evidence. This kind of analysis can only be carried out at a synchrotron due to the intense brightness of the X-rays allowing the weak signals from such trace elements to be significantly detected.

Well I hope you have enjoyed that brief insight into some of the more unusual science that goes on here at Spring8. As a final present I’ll leave you with an image from my first attempts at electron microscopy. This is a microtubule, one of the protein structures involved in maintaining the internal organization of cells, at 70,000 times magnification.

So what really amazes or inspires you from your chosen path in life? What keeps you doing the things you do?

Mata ne minna,