In this edition:
- Raindrops could power devices
- Scientists regrow heart – and it beats
- Mutant super-cockroaches from space
- A molecule chews up uranium contamination
Here's something residents of cloudy northern Europe should appreciate: a way of using rain to generate power.
Jean-Jacques Chaillout and colleagues at the Atomic Energy Commission (CEA) in Grenoble, France, have shown that piezoelectric materials, which generate voltage in response to mechanical force, can be made to produce useful amounts of electrical power when hit by falling rain. "We thought of raindrops because they are one of the still- unexploited energy sources in nature," Chaillout says.
His team started by looking up data on different types of rainfall. Drizzle, they found, produces droplets of about 1 millimetre in diameter which have an impact energy of around 2 microjoules, while droplets from a downpour were typically 5 millimetres across and gave 1 millijoule of impact energy.
The team then used computer simulations to see how different-sized drops hit surfaces and concluded that a 25-micrometre-thick piezoelectric material would be... (source)
My comment: Funny, I was thinking just the same a month or two ago-how many natural resources we let unexplored. Like if we have a house, what could we do to optimally use the renewable energy sources around it. Which will include sun, wind, water (though I must admit I wanted to put turbines on the way of the waste rain-water). But this one is even cooler. I just hope it reaches the market cheap enough.
Rat hearts have been stripped of their cells, repopulated with fresh ones, and made to beat again in a pioneering experiment that could lead to novel treatments for human patients.
You can engineer heart tissue in the lab, but building the whole organ from scratch is tricky, due to its intricate network of blood vessels. Whole organs have therefore been limited to thin structures, including bladders and skin.
But now Doris Taylor at the University of Minnesota in Minneapolis, US, and colleagues have "decellularised" rat hearts by adding chemicals that break up cells, leaving behind just the connective tissue, which is made of proteins.
They found that the resulting scaffolds still have the heart's complex three-dimensional shape, including space for all the blood vessels.
They seeded the scaffolds with blood vessel and heart muscle cells from newborn rats and flowed a soup of nutrients through the scaffold. The seed cells migrated throughout the structure and grew into muscle and blood vessels.
The team also applied small electrical jolts to trigger beating. Within four days, the tissue had started to contract, and within just 8 days the new heart was pumping with 2% of the efficiency of an adult heart. (source)
My comment: I already wrote about this, but repeating won't heart. And it's way too great anyway.
The first creatures ever conceived in space also grew more quickly than ordinary Earth-bred cockroaches. (source)
My comment: Ok, this is a funny one. But it's interesting to see what free fall and radiation can do to a living thing.
3D tissue printer
3D printers have been around for a few years now. They work by printing a structure in layers, one on top of the other, to form complex 3D shapes. Now James Yoo at the Institute of Regenerative Medicine at Wake Forest University in North Carolina, US, says he can do the same thing with living cells.
Yoo uses a standard inkjet printing mechanism to create layers of viable cells, which can then be built into 3D structures. He says the structures may comprise several different types of cells, just as conventional image printers use several different colours of ink.
Yoo says his printer can make almost anything from skin and bone to pancreatic or nerve tissue – an exciting idea with huge potential.
My comment: I thought this is an old one, but there it is again.
Uranium leaches into groundwater from natural deposits of its ore, depleted uranium munitions, nuclear facilities and the detritus of uranium mining. It occurs most commonly in the form of the water-soluble uranyl ion, (UO2)2+, in which the uranium atom is linked to two oxygen atoms by double bonds.
Allowing uranyl to react with other substances might change it into a different, insoluble ion, which can be filtered out. But uranium binds very strongly to oxygen - the bonds it forms are 25 per cent stronger than typical double bonds - making the uranyl ion very stable. Combined with its solubility, this makes dissolved uranium virtually impossible to remove. "It's a very problematic, persistent groundwater contaminant," says Polly Arnold, a chemist at the University of Edinburgh in the UK.
Arnold's colleague Jason Love had been working on improving catalysts for fuel cells using a large organic molecule known as a macrocycle, that can fold in half to form a structure like a pair of jaws. Love was using the gap between the jaws to capture a pair of cobalt ions, but Arnold realised that it was just the right size and shape to clamp onto a uranyl ion.
When she added the macrocycle molecule to uranyl ions dissolved in an organic solvent, she found that it did indeed capture them in its jaws, leaving one oxygen atom protruding (Nature, DOI: 10.1038/nature06467). What's more, a silicon-containing compound present in the mixture was able to bind to the protruding oxygen atom, a sign that the uranyl's stubborn bonds with oxygen had been weakened.
Because the macrocycle is destroyed by water, it cannot be used to remove uranium from contaminated water. But Arnold's team believe their demonstration that the uranyl ion's bonds can be loosened is a first step towards finding substances that can transform dissolved uranyl into an insoluble compound.
The Edinburgh team will also investigate how some bacteria and iron-rich minerals reduce uranium concentrations naturally in contaminated water, and whether the macrocycle is able to loosen bonds in ions containing plutonium. (source)