This summer, the sun will be at its most active for eleven years, spitting out enormous, energetic flares of hot gas and plasma into the solar system. Inevitably, some of this high-energy material will head for earth and could smash into navigation, weather and telecommunications satellites in orbit around the planet.
Now, Canadian researchers have devised a simple plastic coat that could help protect, in future, protect satellite's from damage.
Ian Manners and his team at the University of Toronto are experimenting with electrically conducting poly(ferrocenylsilane), a material based on the iron metallocene ferrocene and a silicon backbone to see whether they can protect the delicate electronics inside every satellite from electrical discharge induced by solar energy.
Spacecraft are continually threatened by high-energy particles and electromagnetic disturbances because of solar flares, which cause damaging electric arcing across components. There have been several instances over the last few years when solar activity has wreaked havoc on telecoms systems. Manners' material will not be ready in time to protect satellites against the peak solar activity this year but will likely be in production in time for the next solar storms in eleven years.
I Manners et al, Advanced Materials, 2000, 12, 327.
Haemophiliacs might one day avoid the needle thanks to an implant being developed by US scientists.
Haemophilia is a hereditary disease affecting 1 in 5000 people, that leaves patients lacking critical proteins that help their blood clot. The smallest cut or bruise can be life-threatening. Treatment usually involves infusing patients with the missing molecules - serine protease (coagulation Factor IX), or its co-enzyme, Factor VIII extracted from 'normal' blood. The infusions are expensive, painful and carry a risk of transmitting disease.
Researchers have developed artificial versions of the clotting factors which can be administered at home, but about a quarter of patients have a dangerous immune reaction to these compounds.
Now, Harvey Pollard of the Uniformed Services University School of Medicine in Bethesda, Maryland, and his team have built an implantable device that circumvents all the problems of infusion and avoids the risk of an allergic reaction.
The device is based on a semi-permeable chamber inside which are tiny polymer beads coated with the clotting Factors Xa or XIIa, which are purified from human blood plasma. When a patient's blood diffuses into the chamber their Factor VII reacts with the Factor XIIa on the beads and splits it into its active form, Factor VIIa, which then diffuses from the device into the blood. This released factor then triggers Factor X into action as Factor Xa which induces the blood coagulation process 'normally'.
Tests on monkeys so far, are positive with the implant working for about a month.
H. Pollard et al, Nature Biotechnology, 2000, 18, 289
A material that can eat smog whatever the weather has been developed by Japanese scientists. The material based on a mixture of the 'whiter than white' pigment titanium dioxide, used in cosmetics and dyes, and activated graphite could be incorporated into construction materials for buildings, bridges and motorway sound baffles to cut down pollution.
Dr Koji Takeuchi and his research team at the National Institute of Resources and Environment in Ibaraki have found that titanium dioxide powder mixed with graphite can soak up nitrogen and sulphur oxide gases - NOx and SOx - from the air. These gases are a major source of pollution from vehicle exhausts and accumulate in busy cities and along motorways.
'Purifying the air is not as simple as purifying polluted water,' explains, 'Takeuchi, 'it is impossible to hold air in one place and wind and air currents spread and dissipate air-borne pollutants.' There are already filters on the ventilation towers of many tunnels and underground carparks in Japan but these use a lot of energy to scrub the polluted air emerging into the atmosphere, he adds. A cheaper solution based on simply absorbing the gases into an active material would be much more environment friendly.
Absorbing the gases is not enough to be useful though so Takeuchi has experimented by shining ultraviolet light on test materials that had absorbed the polluting gases. They found that even weak UV light activated the titanium dioxide to break down the NOx and SOx into weak solutions of nitric and sulphuric acid, which cannot evaporate into the air.
Takeuchi says that incorporating this smog-eating material into construction components such cladding for high-rise buildings could act as a pollution sponge soaking up noxious gases from even the most heavily polluted cities. The UV rays from sunlight, on the cloudiest of winter days, is enough, he claims, to make the material work. The panels would in effect be self-cleaning and so stay white.
At the chemical level, the graphite, which is powdered to produce an enormous surface area in a small volume, acts as a sponge absorbing the pollutants from the air. The titanium dioxide activated by UV light from the sun releases highly reactive oxygen and hydroxy 'radicals' - molecules with an extra electron. These radicals race around inside the material reacting with the absorbed pollutant molecules and zapping them into non-volatile acids.
But what about getting rid of the acids? The material regenerates itself when it comes into contact with water, so when it rains the acids are flushed off into gutters where they can be neutralised by addition of alkali lime in the drainage inlet system leaving refreshed walls ready to eat yet more smog. However, Takeuchi points out, alkali components in the atmosphere also help neutralise the acids as they form so the lime might not be needed.
To make a smog-eating panel the team coated a sheet of fluorocarbon plastic, similar to Teflon, with a thin layer of the titanium dioxide mixture. The fluorocarbon makes for a very tough backing that can resist the weather and because it is difficult enough to make anything stick to it in the first place it becomes almost impossible for the titanium layer to come off! Accelerated weathering tests show the panels should last at least five years.
A panel just one metre square weighs half a kilo and can absorb and destroy several grams of NOx and SOx before it needs to be regenerated, which is enough to last a week or so in even the most polluted of Japan's cities.
Large-scale trials are now underway in Tokyo, Takeuchi told us, and if they work as well as he hopes the materials will become widely used in the construction industry for panelling buildings and pavements, be built into motorway sound barriers or tunnel and car park ventilation towers. He adds that the panels would effectively be maintenance free requiring only a little sun to work and a spot of rain to wash them once a week, or so.
Early results from the tests show that the panels can remove up to 30% of the pollution from the notoriously polluted Tokyo air as well as helping clarify things in other Japanese cities. This simple modification to the urban landscape in this way might be a far more preferable approach to dealing with pollution than simply introducing ever stricter regulations on vehicle use. It might even be possible to reduce traffic volumes enough without a blanket ban to compete with Takeuchi's system.
He and his team are now working on paints that could simply be sprayed on to suitable surfaces and would avoid the need for panels. He is also tweaking the formulation so that the material works in normal light and not just UV, this he says, would boost the effect ten times.
Takeuchi's work is reported in the current issue of the Journal of Environmental Monitoring.