Experimental feature

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Experimental feature

Beetle-inspired material

Scientists have produced a new material that can capture and control tiny amounts of water by examining the moisture-collection system of the Namib Desert beetle which lives in one of the driest regions in the world.

The dime-sized beetle, named after its desert home in Southwest Africa, survives by collecting the water contained in an early morning fog which is so light that normal condensation cannot take place.

But when the fog blows across the surface of the beetle’s back, tiny water droplets millionths of a metre in diameter start to accumulate on top of bumps on its back.

The bumps are superhydrophilic or attract water but are surrounded by waxy superhydrophobic, or water-repelling, channels. The moisture in the air collects on the bumps, getting bigger and bigger until they roll down into the beetle’s mouth.

Inspired by the resilient bug, researchers at MIT decided to create a material with the same abilities by manipulating two characteristics - roughness and nanoporosity (spongelike capability on a nanometre scale).

Glass or plastic substrate was dipped multiple times into solutions of charged polymer chains dissolved in water in order, adding layers to reach an optimum level of texture and porosity. Silica nanoparticles are then added to create an even rougher texture that helps trap water droplets.

The material is then coated with a Teflon-like substance, making it water-repellent. Then layers of charged polymers and nanoparticles can be added in certain areas using a water/alcohol solvent mixture, thereby creating a water-attracting pattern.

The scientists say that the new material could have potential applications for harvesting water, making a miniature diagnostic lab, making microfluidic and cooling devices. The US military have also shown interest in the material as a decontaminating surface that could channel and collect harmful substances.

Massachusetts Institute of Technology: http://web.mit.edu/

Self-heating cup

If you were an emergency worker with no access to electricity and several hours of work ahead of you, a cup of coffee that can heat itself up to a temperature perfect for drinking might be just the thing to give you the strength to keep going.

At least this is what the Russian inventors of a self-heating cup argue.

Bargan Production Group have applied for a worldwide patent for their product, although by the team’s own admission it needs to find a more catchy name for “the packing for changing temperature of the kept product prior to its opening”.

The cup consists of cup arranged in layers like a stack of Russian dolls. By pressing on its side it is possible to heat the contents up to nearly boiling temperature within minutes.

The liquid in the cup is heated by a chemical reaction between zinc and copper sulphate well known to any child who pays attention in chemistry class. The active zinc displaces copper from the sulphate, accompanied by a generation of copper and heat.

However, for the technology to be usable, the scientists had to control the reaction so that the necessary amount of heat was produced within a reasonable time and also to direct the heat towards the liquid rather than anything else in the immediate environment.

The inventors had to balance a myriad of parameters to reach their goal including the reagent’s ratio and quantity, size of their particles and even the number of molecules of water in copper sulphate crystalline hydrate - all of these factors influenced the process rate and intensity.

Finally, the Bargan team hit upon the right heat-generating formula (a mixture of copper sulphate and zinc powder) which heated a glass of water up to 70 degrees centigrade within about five minutes and 90 degrees centigrade in 9 minutes.

The design of the cup was crucial to preserving the heat. The team decided on a multilayered design with four cups sitting within each other like a set of nesting Russian dolls.

One cup holds the beverage, while the outer one is made of heat-insulating polystyrene. Between them is what the team call a “thermal module”. These are small cups filled with a mixture of reagents, a small tank of water for sparking the reaction and a sharp needle made of stainless steel.

To initiate the heating process a user simply presses on the side and the needle pierces a “bag” of water which leaks on the reagents. Once the beverage has been heated it is ready to drink.

Each cup only works once and full will weigh about 300g compared to 352g for a standard beverage can (0.33 litres).

Taking blood in space

Taking blood from an artery in space can be a difficult and dangerous process - especially in low gravity conditions - but could prove critical in diagnosing health emergencies.

Arterial blood - blood coming fresh from the heart - is preferable for accurate diagnosis to blood from the vein because the latter has been de-oxygenated and altered in the body’s tissues. This particularly true of testing for the efficiency of a patient’s ventilation or for the pH of his or her blood which can be used determine whether the patient is getting more or less sick.

But to collect blood from the artery is more complicated and can be painful and lead to blood clots or infection - making it dangerous to perform in space.

Now, according to NewScientist.com, scientists at Brazil’s PUCRS university have invented a solution - a thumb-sized gadget that collects a sample of “arterialised blood” from the earlobe.

The device contains a small blade and collects blood painlessly in a chamber to prevent spillage and contamination. It clips on to the ear and is operated by a quick twist.

The system has already been tested in microgravity conditions. Now the team, which also includes researchers from Thames Valley University in the UK, is hoping for a trial on board the International Space Station.

PUCRS: http://www.pucrs.br/

Thames Valley University: http://www.tvu.ac.uk/index.jsp

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