Food dye at the spinal frontier

Scientists have discovered that a dye used to colour food can also help to heal spinal injuries. Writing in this week's PNAS, a team at the University of Rochester led by Maiken Nedergaard describe how a dose of Brilliant Blue G, an analogue of the food dye FD&C blue dye No. 1, can help rats with cord injuries to recover better than controls. The effect, say the team, is down to the ability of the dye to block a class of nerve transmitter receptors known as P2X7 receptors, which are present on spinal nerves and respond to chemical signals called purines, including one called ATP. Purines are released in large abundance during spinal injuries.

When they lock onto P2X7 receptors a large pore is formed on the target nerve cell which allows large amounts of calcium and other potentially toxic substances to enter and kill the cell. This contributes significantly to what is known as "secondary damage" that often follows an injury and is responsible subsequently for a significant disability. The team had previously identified a chemical capable of blocking P2X7receptors, OxATP, which had shown promise in reducing spinal cord injury but it was highly toxic to other tissues, ruling out any therapeutic role for the agent. But this prompted the team to look for other substances capable of doing the same job, leading them to Brilliant Blue G (BBG). To test its effectiveness the team subjected experimental rats to spinal cord injuries.

Some of the animals received BBG whilst others were left untreated as controls. The researchers found that the BBG-treated animals began to recover sooner than the controls and regained superior function subsequently. And when the team compared the spinal cord tissue from the animals they found that the treated rats had significantly less secondary spinal tissue loss than the controls. The team point out that given the proven safety record of BBG this strategy could make a significant contribution to the management of spinal and other central nervous system injuries. At present, they point out, steroids like methyl prednisolone are about the best that doctors can offer a spinal injury patient. Steroids have modest benefit and work by reducing inflammation at the injury site but there is a delay before they begin to work. The effect of BBG is instantaneous, say the scientists, so it could have much to offer...

2nd Aug 2009

Put a shrimp in your tank

You’ve heard of putting a tiger in your tank, but now how about putting a shrimp in your tank? Doesn’t sound quite so impressive does it? But, that’s exactly what scientists in China have been doing in an attempt to make biodiesel production more efficient.

XinshengZheng and colleagues from HuaZhong Agriculture University in Wuhan have discovered that shrimp shells could be a great improvement on the catalysts currently used to convert natural oils – from crops like soya,sunflowersand rapeseed – into diesel fuels for vehicles.

The use of biofuels is fraught with controversy. One possible way to get closer to a sustainable source of renewable fuel is to improve the yield of fuel per acre of crop.

Making biodiesel involves a process known as transesterification, which is essentially changes the chemical makeup of fatty acids in seed oils to convert them into a useable fuel. The reaction normally takes place very slowly, if at all, with the addition of a simple alcohol like methanol.

Traditionally it is speeded up and made more efficient by adding a catalyst in the form of a strong acid or base. The problem with these acid and base catalysts is they can’t be reused and they involve the use of lots of water, another limited resource.

Now it seems shrimp shells could provide an alternative, more efficient catalyst that can be reused and doesn’t need masses of water. Shrimp shell is made up mostly of chitin, the same stuff that our nails and hair are made of. By carbonizing – or burning – the shells and adding potassium fluoride,Zheng and the team made a catalyst which, after 3 hours, converted 89% of samples canola oil into biodiesel.

Shrimp shell make aparticularly good catalyst because is it’s complex porous structure with dense honeycomblayers. With such a large internal surface area to the shell fragments there are lots of sites the oils come into contact with and where theesterification reaction will be speeded up, making the conversion to alcohol quicker and more complete.

The authors of the study, which appears in the journal Energy and Fuels, point out that shrimp shell is biodegradable and cheap, being a bi-product of the seafood industry. And while no-doubt the diofueldebate will rage on, they think this new finding could prove to be an important breakthrough in making biofuels more efficient and perhaps a bit less controversial.

Paper: Yang, L, Zhang, A., Zheng, X. 2009. Shrimp shell catalyst for biodiesel production. Energy & Fuels.

2nd Aug 2009

Raindrop sizes explained

In the nineteenth centuary scientists studying the weather looked at raindrop sizes, and discovered something quite interesting. There was quite a variation, most were less than 1mm across but a few were up to 5mm across, but for the same rate of rainfall the distribution was always the same.

This is strange as there are lots of ways in which rain can be created, at different heights and rates, depending on the clouds it is coming from. At the time it was thought that it was because big drops were crashing into one another and breaking apart. The problem is that there just aren't enough raindrops in the sky to crash into each other so scientists have remained confused.

Emmanuel Villermaux at Aix-Marseille University has probably worked out what is going on. There is a well known effect on fast moving droplets of diesel in an engine, where they flatten, then blow up to form a parachute shape and then pop to form smaller droplets.

This is an effect I noticed on a high speed video of our water rockets kitchen science experiment. right at the end of this video, watch the last water droplet falling.