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John Roach
for National Geographic News

November 19, 2008


ON TV Lost Cities of the Amazon airs Thursday, November 20, at 9 p.m. ET on the National Geographic Channel. Details >>

Centuries-old European explorers' tales of lost cities in the Amazon have long been dismissed by scholars, in part because the region is too infertile to feed a sprawling civilization.

But new discoveries support the idea of an ancient Amazonian urban network—and ingeniously engineered soil may have made it all possible.

(See Ancient Amazon Cities Found; Were Vast Urban Network [August 28, 2008].)

Now scientists are trying to recreate the recipe for the apparently human-made supersoil, which still covers up to 10 percent of the Amazon Basin. Key ingredients included of dirt, charcoal, pottery, human excrement and other waste.

If recreated, the engineered soil could feed the hungry and may even help fight global warming, experts suggest.

(Interactive map: "The Embattled Amazon.")

Before 1492

Scientists have long thought the river basin's tropical soils were too acidic to grow anything but the hardiest varieties of manioc, a potatolike staple.

But over the past several decades, researchers have discovered tracts of productive terra preta—"dark earth." The human-made soil's chocolaty color contrasts sharply with the region's natural yellowish soils.



Video Clip From
Lost Cities of the Amazon Documentary





Research in the late 1980s was the first to show that charcoal made from slow burns of trees and woody waste is the key ingredient of terra preta.

With the increased level of agriculture made possible by terra preta, ancient Amazonians would have been able to live in one place for long periods of time, said geographer and anthropologist William Woods of the University of Kansas.

"As a result you get social stratification, hierarchy, intertwined settlement systems, very large scale," added Woods, who studies ancient Amazonian settlements.

"And then," he said, "1492 happens." The arrival of Europeans brought disease and warfare that obliterated the ancient Amazonian civilizations and sent the few survivors deep into the rain forest to live as hunter-gatherers.

"It completely changed their way of living," Woods said.

Magic Soil?

Today scientists are racing to tease apart the terra-preta recipe. The special soil has been touted as a way to restore more sustainable farming to the Amazon, feed the world's hungry, and combat global warming.

The terra-preta charcoal, called biochar, attracts certain fungi and microorganisms.

Those tiny life-forms allow the charcoal to absorb and retain nutrients that keep the soil fertile for hundreds of years, said Woods, whose team is among a few trying to identify the crucial microorganisms.

"The materials that go into the terra preta are just part of the story. The living member of it is much more," he said.

For one thing, the microorganisms break up the charcoal into smaller pieces, creating more surface area for nutrients to cling to, Woods said.

Anti-Global-Warming Weapon?

Soil scientist Johannes Lehmann of Cornell University is also racing to recreate terra preta.

The Amazonian dark soils, he said, are hundreds to thousands of years old, yet to this day they retain their nutrients and carbons, which are held mainly by the charcoal.

This suggests that adding biochar could help other regions of the world with acidic soils to increase agricultural yields.

Plus, Lehmann said, biochar could help reduce the amount of greenhouse gas emissions released into the atmosphere from the burning of wild lands to create new farm fields. (Learn how greenhouse gas emissions may worsen global warming.)

For example, specialized power plants could char agricultural wastes to generate electricity.

The process would "lock" much carbon that would have otherwise escaped into the atmosphere in the biochar. The biochar could then be put underground, in a new form of terra preta, thereby sequestering the carbon for centuries, Lehmann suggests.

Current Amazonian farming relies heavily on slash-and-burn agriculture—razing forests, then burning all of what's left.

By reverting to the ancient slash-and-char method—burning slowly and then mixing the charcoal into the soil—Amazonian carbon dioxide emissions could be cut nearly in half, according to Woods, of the University of Kansas.

With slash-and-burn, he noted, 95 percent of the carbon stored in a tree is emitted to the atmosphere. Slash-and-char emits about 50 percent, he said.

"The rest is put into different forms of black carbon, most of which are chemically inert for long periods of time—thousands of years."

In addition, the technique would allow many farmers to stay sedentary, Woods said.

Because the soil would apparently remain fertile for centuries, "they don't have to cut down the forest constantly and send it up into the atmosphere," he said.

A MIRACLE material for the 21st century could protect your home against bomb blasts, mop up oil spillages and even help man to fly to Mars.

Aerogel, one of the world’s lightest solids, can withstand a direct blast of 1kg of dynamite and protect against heat from a blowtorch at more than 1,300C.

Scientists are working to discover new applications for the substance, ranging from the next generation of tennis rackets to super-insulated space suits for a manned mission to Mars.

It is expected to rank alongside wonder products from previous generations such as Bakelite in the 1930s, carbon fibre in the 1980s and silicone in the 1990s. Mercouri Kanatzidis, a chemistry professor at Northwestern University in Evanston, Illinois, said: “It is an amazing material. It has the lowest density of any product known to man, yet at the same time it can do so much. I can see aerogel being used for everything from filtering polluted water to insulating against extreme temperatures and even for jewellery.”

Aerogel is nicknamed “frozen smoke” and is made by extracting water from a silica gel, then replacing it with gas such as carbon dioxide. The result is a substance that is capable of insulating against extreme temperatures and of absorbing pollutants such as crude oil.

It was invented by an American chemist for a bet in 1931, but early versions were so brittle and costly that it was largely consigned to laboratories. It was not until a decade ago that Nasa started taking an interest in the substance and putting it to a more practical use.

In 1999 the space agency fitted its Stardust space probe with a mitt packed full of aerogel to catch the dust from a comet’s tail. It returned with a rich collection of samples last year.

In 2002 Aspen Aerogel, a company created by Nasa, produced a stronger and more flexible version of the gel. It is now being used to develop an insulated lining in space suits for the first manned mission to Mars, scheduled for 2018.

Mark Krajewski, a senior scientist at the company, believes that an 18mm layer of aerogel will be sufficient to protect astronauts from temperatures as low as -130C. “It is the greatest insulator we’ve ever seen,” he said.

Aerogel is also being tested for future bombproof housing and armour for military vehicles. In the laboratory, a metal plate coated in 6mm of aerogel was left almost unscathed by a direct dynamite blast.

It also has green credentials. Aerogel is described by scientists as the “ultimate sponge”, with millions of tiny pores on its surface making it ideal for absorbing pollutants in water.

Kanatzidis has created a new version of aerogel designed to mop up lead and mercury from water. Other versions are designed to absorb oil spills.

He is optimistic that it could be used to deal with environmental catastrophes such as the Sea Empress spillage in 1996, when 72,000 tons of crude oil were released off the coast of Milford Haven in Pembrokeshire.

Aerogel is also being used for everyday applications. Dunlop, the sports equipment company, has developed a range of squash and tennis rackets strengthened with aerogel, which are said to deliver more power.

Earlier this year Bob Stoker, 66, from Nottingham, became the first Briton to have his property insulated with aerogel. “The heating has improved significantly. I turned the thermostat down five degrees. It’s been a remarkable transformation,” he said.

Mountain climbers are also converts. Last year Anne Parmenter, a British mountaineer, climbed Everest using boots that had aerogel insoles, as well as sleeping bags padded with the material. She said at the time: “The only problem I had was that my feet were too hot, which is a great problem to have as a mountaineer.”

However, it has failed to convince the fashion world. Hugo Boss created a line of winter jackets out of the material but had to withdraw them after complaints that they were too hot.

Although aerogel is classed as a solid, 99% of the substance is made up of gas, which gives it a cloudy appearance.

Scientists say that because it has so many millions of pores and ridges, if one cubic centimetre of aerogel were unravelled it would fill an area the size of a football field.

Its nano-sized pores can not only collect pollutants like a sponge but they also act as air pockets.

Researchers believe that some versions of aerogel which are made from platinum can be used to speed up the production of hydrogen. As a result, aerogel can be used to make hydrogen-based fuels.

Power station harnesses Sun's rays

By David Shukman Science correspondent, BBC News, Seville A field of 600 mirrors reflects rays from the Sun A tour of the tower How the solar tower works There is a scene in one of the Austin Powers films where Dr Evil unleashes a giant "tractor beam" of energy at Earth in order to extract a massive payment. Well, the memory of it kept me chuckling as I toured the extraordinary scene of the new solar thermal power plant outside Seville in southern Spain. From a distance, as we rounded a bend and first caught sight of it, I couldn't believe the strange structure ahead of me was actually real. A concrete tower - 40 storeys high - stood bathed in intense white light, a totally bizarre image in the depths of the Andalusian countryside. The tower looked like it was being hosed with giant sprays of water or was somehow being squirted with jets of pale gas. I had trouble working it out. In fact, as we found out when we got closer, the rays of sunlight reflected by a field of 600 huge mirrors are so intense they illuminate the water vapour and dust hanging in the air. The effect is to give the whole place a glow - even an aura - and if you're concerned about climate change that may well be deserved. It is Europe's first commercially operating power station using the Sun's energy this way and at the moment its operator, Solucar, proudly claims that it generates 11 Megawatts (MW) of electricity without emitting a single puff of greenhouse gas. This current figure is enough to power up to 6,000 homes. But ultimately, the entire plant should generate as much power as is used by the 600,000 people of Seville. It works by focusing the reflected rays on one location, turning water into steam and then blasting it into turbines to generate power. As I climbed out of the car, I could hardly open my eyes - the scene was far too bright. Gradually, though, shielded by sunglasses, I made out the rows of mirrors (each 120 sq m in size) and the focus of their reflected beams - a collection of water pipes at the top of the tower. It was probably the heat that did it, but I found myself making the long journey up to the very top - to the heart of the solar inferno. David had to wear sunglasses to shield his eyes from the glare A lift took me most of the way but cameraman Duncan Stone and I had to climb the last four storeys by ladder. We could soon feel the heat, despite thick insulation around the boiler. It was like being in a sauna and for the last stages the metal rungs of the ladders were scalding. But our reward was the cool breeze at the top of the tower - and the staggering sight of a blaze of light heading our way from down below. So far, only one field of mirrors is working. But to one side I could see the bulldozers at work clearing a second, larger field - thousands more mirrors will be installed. Letting off steam I met one of the gurus of solar thermal power, Michael Geyer, an international director of the energy giant Abengoa, which owns the plant. He is ready with answers to all the tricky questions. What happens when the Sun goes down? Enough heat can be stored in the form of steam to allow generation after dark - only for an hour now but maybe longer in future. Anyway, the solar power is most needed in the heat of summer when air conditioners are working flat out. Is it true that this power is three times more expensive than power from conventional sources? Yes, but prices will fall, as they have with wind power, as the technologies develop. Also, a more realistic comparison is with the cost of generating power from coal or gas only at times of peak demand - then this solar system seems more attractive. The vision is of the sun-blessed lands of the Mediterranean - even the Sahara desert - being carpeted with systems like this with the power cabled to the drizzlier lands of northern Europe. A dazzling idea in a dazzling location. HOW THE SOLAR TOWER WORKS 1. The solar tower is 115m (377ft) tall and surrounded by 600 steel reflectors (heliostats). They track the sun and direct its rays to a heat exchanger (receiver) at the top of the tower 2. The receiver converts concentrated solar energy from the heliostats into steam 3. Steam is stored in tanks and used to drive turbines that will produce enough electricity for up to 6,000 homes

Alarming Disappearance of Honey Bees

© 2007 by Linda Moulton Howe

"This is certainly the worst die-off that I’ve seen in my experience workingwith honey bees. It may be the worst die-off that has ever occurred with honey beessince they’ve been introduced into the United States since the 1620s." - Maryann Frazier, Honey Bee Specialist, Penn State

Most people don’t realize that honey bees pollinate about one-third of our food supply around the world. Honey bees pollinate apple trees and berry bushes, vegetables, melons, almonds and many other food sources. Honey bees were originally brought from Europe to the United States in 1620. Periodically since then, there have been occasional die-offs of honey bees, mostly attributed to mites.

But according to the scientists, beekeepers and government agency bee specialists I’ve talked to recently, there have never been so many empty, deserted honey bee hives as there are now. And no one knows why.The past year in America, at least 22 states have reported honey bee disappearances. Government and science authorities are calling it "Colony Collapse Disorder (CCD)." Beekeepers have reported losses ranging from 60% to 100% of their bee colonies. As winter changes to spring and beekeepers in the colder Northeast can open their hives again, it's expected there will be many more empty hives. Strangely, honey bees have also been disappearing in huge numbers in Spain and Poland. Adding to the European mystery is that Spain has very large commercial beekeeper operations with at least 3 million colonies of honey bees, similar to the United States. But Poland’s 400,000 hives are largely raised on individual farms where smaller bee colonies are separated from each other. If the answer were disease, you would not expect Poland’s separated hives to be plagued by large numbers of honey bee disappearances as in Spain and the United States.

The two European countries with the largest honey bee populations are France and Italy. It might be significant that those two countries banned certain pesticides in recent years because beekeepers there became convinced that systemic pesticides were killing off honey bees. And so far, neither France nor Italy has yet reported the collapse of honey bee hives.One scientist who has been studying honey bees at Penn State University for the past eighteen years is Maryann Frazier. I asked her how serious she thinks the honey bee disappearances are.

Interviews:

Maryann Frazier, M. S., Honey Bee Extension Specialist, Dept. of Etymology, Penn State University, College Park, Pennsylvania: “I would say this is certainly the worst die-off that I’ve seen in my experience working with honey bees. It may be the worst die-off that has ever occurred with honey bees since they’ve been introduced into the United States since the 1620s.

It’s characterized by the bees being there in the colony quite healthy and strong on one day and then within a week to two weeks, the beekeeper goes back and the bees have disappeared from the colony. Sometimes (there will be) a queen and a small number of bees – often times there is brood, which is the young, developing bees. Some how the bees have just gone and we assume died outside the hive. There is no evidence that the bees have congregated anywhere, or tried to swarm – there is no evidence of that. The bees are just missing! A very unusual kind of situation.

WE’RE TALKING THEN ABOUT THE MYSTEROUS DISAPPEARANCE OF BEES IN THE MILLIONS AND THAT MUST PRESENT A PROBLEM IN DOING SOME KIND OF AUTOPSY TO FIND OUT WHAT IS HAPPENING?

That’s right. It is very difficult to find out what is happening. We do have some strong leads about what might be happening and that has come from beekeepers who we have interviewed at great length and tried to come up with common threads, things these beekeepers might have in common that might explain some of what is happening."

Beekeeper Suspects Systemic Pesticides

One of those large American beekeepers is David Hackenberg, owner of Hackenberg Apiaries in Lewisburg, Pennsylvania. Mr. Hackenberg has been raising honey bees for both commercial honey sales and for pollination in Florida and California crops over the past 45 years. He trucks his pollinating honey bees to farmers who hire his pollination services.

But in October 2006, something hit his honey bees hard and by the beginning of 2007, he has lost at least 60% of his colonies. Dave Hackenberg suspects that the culprit in this unprecedented honey bee disappearance is systemic pesticides – poisons designed to stay inside plants and kill off insects that damage crops. Systemic pesticides are not supposed to kill off honey bees, but David Hackenberg explains why he thinks that’s the problem.

David Hackenberg, Owner, Hackenberg Apiaries, Lewisburg, Pennsylvania:

“We move bees up and down the East Coast. We moved the last of our bees in October 2006. And a month later, in early November, we went out to look at some bees and the first location we found had disappeared. It had 400 hives of bees in it and in less than four weeks, they had just disappeared. Empty boxes. No dead bees on the ground. No dead bees anywhere.

SO IT IS REALLY A DISAPPEARANCE MORE THAN A DIE-OFF BECAUSE YOU DON’T HAVE BODIES?

That’s absolutely right! The bees have died – I mean they’ve died some place, but nobody knows where they are – whether they flew off a mile or two miles or what to die. I mean, we just don’t know how far out they are going.

IN THAT FIRST DISAPPEARANCE OF ALL THOSE BEES FROM YOUR HIVES, HOW MANY BEES DID YOU LOSE?

Those beehives would have had somewhere around 20,000 or 30,000 bees per hive and if you take that times roughly 400, you’re talking about millions of bees disappearing.

WHAT HAVE YOU SEEN DISAPPEARING SINCE THE FALL?

We had 2900 hives of bees here in October 2006, and we’re down to less than 1,000 now. So, we’ve lost some 60% of them.

HAVE YOU EVER HAD THIS HAPPEN BEFORE?

No, this is the worst thing that’s ever happened to us. I’ve seen a lot of things come down the pike. I’ve been through mites. I’ve been through fires. I’ve been through floods. I’ve had warehouses burn to the ground.

I’ve had 10 feet of water in my warehouse. And I know what caused that!

And I know what caused the fire. And I know what caused the problem we had with mites. But the problem here (now) is that we don’t know – I just shudder to think what things might look like next year.

In this case, the thing that is really amazing is that (normally) other bees will come in and rob out the honey that’s left and there are a few predators.

Here in the south, we have a hive beetle that moves in and we have a wax moth that moves in and starts eating up comb and stuff. The interesting thing about this whole thing is that none of these (normal) things happen.

The bees do not bother these (deserted) combs. They (honey combs) literally sit there for weeks and they (other bees and insects) don’t come to take the honey out of the boxes; the beetles don’t bother them; the wax moths don’t bother them. So, it’s just like there is something in there that’s repelling everything else.

AS IF THE HONEY ITSELF THAT WAS MADE BY ALL OF THE BEES THAT HAVE DISAPPEARED IS GIVING OFF SOMETHING THAT OTHER NORMAL PREDATORS AND BEES ARE STAYING AWAY FROM?

There’s something in the hive. We’re pretty sure the honey is not the problem because once you air out this hive for a day or so, they (other bees) will take the honey. And if you air the hive out, the beetles, wax moths and everything else will take over. So, there’s some toxic odor, some other – fortunately some of these colonies are still living and we found this here in Florida and we beat if back to Penn State with it - and thinking basically we had a new virus problems, but found out the bees are full of a fungus. And we think this fungus is giving off some toxins. Personally I think the fungus is probably secondary from something else – poisonous pollen or something that was gathered by the bees.

DAVE, WHAT WOULD IT MEAN IF THERE WAS SOME KIND OF CONTAMINATED POLLEN IN 22 STATES?

It actually means that there is probably a big problem out here. It’s probably a lot wider than most of us want to think about. There’s a possibility that there’s some new insecticide or some new something that is being applied to the crops or being used, but is being transferred into this pollen that bees are gathering and bringing back to the hive – that it’s coming up through the plant, remains to be seen. But it sure appears that way. There are new products out there that are systemic, which means they stay in the plant. So, not only staying in the plant, but it’s probably going in the food that we’re eating and the animals are eating and everybody else is eating with really serious ramifications to this thing.

THAT WE COULD BE JUST AT THE TIP OF AN ICEBERG HERE?

Personally, I think that’s the case. I’ve had several people in Washington, D. C., in the last several months telling me that honey bees are a canary for the human race. The canary is what was used in mines to see whether there was oxygen, or not enough oxygen, for the miners. If the canary fell over, why it was time to get out. And Penn State has already found it looks like the immune system has been broken down on these honey bees. So, if the immune system is broken down and this stuff is going into our food supply, how much does it take to take out humans?

You know, I hate to be pessimistic about the situation, but it just doesn’t appear good.

RIGHT, AND WHAT HAPPENS IF ALL THE HONEY BEES DISAPPEAR?

First of all, a third of the food supply in the United States – and actually the world – a third of the food supply is directly related to the honey bee: fruits, vegetables, nuts, just a lot\ of stuff that we eat, that we’re accustomed to have every day, the honey bee is directly responsible for it.

And then, there is probably another 30% of what we consume that honey bees are indirectly responsible for. Take the milk we drink. The cows have to have hay. They’ve got to eat clover and alfalfa to produce milk. And if you go back and listen to what (Albert) Einstein told us – he said if the honey bees disappeared off the face of the Earth, within four years, all life would be gone. Even the wildlife depends on plants pollinated by the honey bees for berries and so on. So, it’s not just humans not being able to get apples and carrots. We’re talking about a real big, serious problem!

WHEN YOU TALKED WITH THE PEOPLE IN THE GOVERNMENT AND THEY SAID THE HONEY BEES WERE LIKE A CANARY DOWN IN THE COAL MINE WARNING THAT IF THE BIRD DIED, THEN THE MINERS MIGHT DIE – WHAT DID THE GOVERNMENT PEOPLE SAY THAT THEY THOUGHT MIGHT BE THE PROBLEM?

They really don’t know. That was in the preliminary stages, but that’s the first time in my 40 some years of beekeeping that anybody had ever said that to me. I mean that was something I’d never heard before.

WHAT YOU MEAN IS THAT OUR ENTIRE FOOD SUPPLY, NOT ONLY IN THIS COUNTRY, BUT ALSO IN OTHER PARTS OF THE WORLD, COULD BE THREATENED AS THE HONEY BEES AND OTHER BEES ARE THREATENED BY WHATEVER IS KILLING THEM?

Yes, that’s exactly right. And actually, we’re hearing from Europe now that Poland and Spain – they have lost astronomically large numbers of bees this past fall.

Even with the losses we’ve got now, there are guys that are telling me there’s no way they are going to be able to replace the losses they have this year. So, if you can’t replace the losses you’ve got this year, and you have another loss on top of it next year, you’re headed down a bad, bad way, that’s all!

AND ESPECIALLY IS IT IRONIC, DAVE, IF THE CULPRIT IS THE CHEMICALS IN PESTICIDES THAT HAVE BEEN DEVELOPED TO ALLOW FARMERS TO GROW CROPS AND IT ENDS UP KILLING THE POLLINATORS.

That’s right.”

Disappearing Pollinators - Could There Be Food Shortages in 2007?

I asked the Acting State Apiarist in Pennsylvania’s Department of Agriculture if he expects any food shortages this year because of the honey bee crisis and what he thinks worst case might be in 2007?

Dennis vanEngelsdorp, M. S., Acting State Apiarist, Pennsylvania Department of Agriculture, Harrisburg, Pennsylvania:

“This situation is unique because we’re not sure what the underlying cause is.

WOULD YOU SAY YOU MIGHT HAVE AN ANSWER IN MARCH?

I think we’ll be able to rule some things out by March. I would be very surprised right now if there was a very large shortage to meet East Coast needs this year. However, if we can’t figure out how to identify this problem, or solve this problem, we could not sustain a loss like this again. That is what differentiates this loss from past losses from the Verroa mite and Honeybee Tracheal mite losses because there is not that number of bees to fill in the void anymore.

AND SO WHAT IS WORST CASE AND WORST CASE CONSEQUENCES?

I think this is a worst case for the beekeepers who experience 80% to 90% loss. That’s terrible! There was one Pennsylvania beekeeper who spent $15,000 to move his colonies to California for almond pollination, and he’s bringing nothing back but dead hives. And that’s worst case for him.”

Mr. van Engelsdorp at the Pennsylvania Dept. of Agriculture has joined up with Penn State researchers, the U. S. Department of Agriculture, the Florida Dept. of Agriculture, and organizations such as Bee Alert affiliated with the University of Montana, to study what is happening to honey bees. The study group recently wrote that the honey bee Colony Collapse Disorder “threatens the pollination industry and production of commercial honey in the United States.” Even honey bees brought here from Australia - to fill in for the disappearing American honey bees - have also disappeared.
Until there is an answer to what is causing the honey bees to leave their hives and never return, it’s possible that eventually there will be honey and other food shortages. 

Although windows can naturally heat buildings in the cold seasons, some hot sunny days might make you wish that windows would just go away.

Scientists from Japan have recently designed new technology that will make windows seem to disappear by turning clear, transparent glass into mirrors.

The group, from the National Institute of Advanced Industrial Science and Technology (AIST), has designed and produced the first full-size sample of switchable mirror glass to be realistically compatible in buildings, houses and cars.

A switchable glass is glass with adjustable transparency or color, or in this case, reflective properties.

Scientists Kazuki Yoshimura and Shanhu Bao experimented with improving the characteristics of previous switchable glass by using magnesium-titanium alloy as the switchable film.

Two glass sheets of 60 x 70 cm (24 x 28 in) made up the window structure, and each had an interior coating of 40-nm-thick magnesium-titanium alloy, plus a 4-nm-thick layer of palladium.

According to Yoshimura and Bao, finding the correct alloy mixture was essential to producing a transparent and energy efficient switchable glass.

Previous attempts at switchable glass faced commercialization problems such as being too expensive (e.g. yttrium and lanthanum), or having a yellowish tint that was unsuitable for cars or clear viewing (e.g. magnesium-nickel).

While other types of switchable glasses have already been commercialized, these varieties tend to have minimal advantages in energy efficiency.

For example, electrochromatic glass, which works by using electrical signals to change color and absorb sunlight, reaches high temperatures that often end up re-radiating infrared radiation in the room.

The switching mechanism in Yoshimura and Bao’s window, on the other hand, is done by altering the gas content between the two glass panes.

By introducing a small amount of hydrogen into the atmosphere between the panes, the glass acts as a transparent window.

Alternatively, adding a small amount of oxygen with no hydrogen forms a reflecting mirror.

“Small amounts of hydrogen and oxygen for use in the switching process can be readily generated by decomposition of water,” the scientists reported.

“The thin film showed excellent switching characteristics. . . . The change between states is very impressive.”

By applying this switchable glass to windows in homes, offices and cars, the scientists estimate that reduced air conditioning needs could result in an energy savings of up to 30%.

Scientists at the AIST are currently working on maximizing the durability of the switchable glass, and overcoming the deterioration that arises due to repeated switching. Also, because the magnesium-titanium alloy can be applied to transparent materials besides glass, more applications may yet be discovered.

-By Lisa Zyga, Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. 

As Australians become increasingly alert to the importance of using water wisely in the home, CSIRO researchers have found a way to use a third less water when you shower – by adding air.

The scientists have developed a simple 'air shower' device which, when fitted into existing showerheads, fills the water droplets with a tiny bubble of air. The result is the shower feels just as wet and just as strong as before, but now uses much less water.

The researchers, from CSIRO Manufacturing Materials Technology in Melbourne, say the device increases the volume of the shower stream while reducing the amount of water used by about 30 per cent.

Given the average Australian household uses about 200,000 litres of water a year, and showers account for nearly a third of this, the 'air shower' could help the average household save about 15,000-20,000 litres a year. If you extend this across the population, that is an annual saving of more than 45,000 Olympic-sized swimming pools.

The Aerated Showerhead creates the sensation of having a full and steady stream of water even though the water is now more like a wet shell around a bubble of air.

While the general concept of using an aerated showerhead to save water is not new, the technology behind the CSIRO's device is novel.

Developed by a team led by Dr Jie Wu, the aeration device is a small nozzle that fits inside a standard showerhead. The nozzle uses a small Venturi tube – a tube for which the diameter varies, creating a difference in pressure and fluid speed. Air is sucked into the Venturi tube as a result of the partial vacuum created, causing air and water to mix, forming tiny bubbles within the water stream.

"The nozzle creates a vacuum that sucks in air and forces it into the water stream," Dr Wu says.

"We make the water droplets in the stream hollow and the bubbles expand the volume of the shower stream."

Small-scale experiments using the aeration device found that people detected no difference in water pressure, sensation, or overall perception of showering.

After almost two years of research and development, CSIRO is ready to take the aerated shower head technology to the commercialisation stage.

"We have very promising results on the aerated showerhead's water-saving potential. Now we are looking for commercialisation partners who will be involved in the development needed to turn the technology into a marketable device," Dr Wu says.

He expects the nozzle would cost less than AUD$20 and could be installed by householders.

Source: CSIRO Australia




This news is brought to you by PhysOrg.com

The Gravity Express

A forty-two minute gravity train route from New York City to HawaiiAbout four hundred years ago– sometime in the latter half of the 17th century– Isaac Newton received a letter from the brilliant British scientist and inventor Robert Hooke. In this letter, Hooke outlined the mathematics governing how objects might fall if dropped through hypothetical tunnels drilled through the Earth at varying angles. Though it seems that Hooke was mostly interested in the physics of the thought experiment, an improbable yet intriguing idea fell out of the data: a dizzyingly fast transportation system.

Hooke's calculations showed that if the technology could be developed to bore such holes through the Earth, a vehicle with sufficiently reduced friction could use such a tunnel to travel to another point anywhere on the on Earth within three quarters of an hour, regardless of distance. Even more amazingly, the vehicle would require negligible fuel. The concept is known as the Gravity Train, and though it seems inconceivably difficult to construct, it has received some serious scientific attention and research in the intervening centuries.The basic concept behind the gravity train is straightforward: At each end of the tunnel, an observer looking into the hole would see a downhill slope. If a train at one end of the tunnel were to release its brakes, the force of gravity would immediately pull the train downhill and cause the train to accelerate much like a roller coaster.

Steeper slopes would result in more speed, with the highest acceleration occurring in the straight-down tunnels which cross the Earth's center. The train would continue to accelerate until reaching the halfway point, at which time its inertia would be at odds with gravity and it would begin to decelerate. As Hooke's data indicates, if the train operated in a frictionless environment it would reach the surface on the opposite end of the tunnel at the exact moment that its speed reached zero. Naturally, a gravity train operating in a real-world environment would need to bring along enough horsepower to make up the friction loss.

One interesting property of the Gravity Express is that its transit time would always be very, very close to forty-two minutes regardless of the distance travelled. In fact, if the Earth were a perfect sphere, the trip time would always be exactly forty-two minutes and twelve seconds. Greater distances would be traversed in the same amount of time as short ones because the train's maximum speed would be increased enough to exactly make up the difference. Due to nature of gravity, this forty-two minute trip time would be consistent for any size of vehicle.

Consider a hypothetical Gravity Express station in Spain which connects to a sister station in New Zealand. The tunnel would be straight down because its route would intersect with the Earth's center, making for an interesting departure as the train entered sudden free-fall. The vehicle would accelerate to a maximum velocity of about 17,670 miles per hour before beginning to decelerate, and it would travel in a straight line for 7,290 miles– a trip which would be 12,440 miles on the surface. Forty-two minutes after their stomach-turning departure, the train and its passengers would pull to a gentle stop at their destination on the other side of the world.

Though Robert Hooke and Isaac Newton corresponded on the subject of objects falling through the Earth, they did so merely as an intellectual exercise. The first serious suggestion to build a gravity train wasn't put forward until the 1800s, presented to the Paris Academy of Sciences by a group of scientific optimists. Unsurprisingly, the Academy opted to defer the ambitious suggestion. The concept was lost to obscurity until the 1960s, when physicist Paul Cooper published a paper in the American Journal of Physics suggesting that gravity trains be considered for a future transportation project. Though the article sparked some lively debate, the proposal was not taken very seriously.

While friction does put a damper on the gravity train concept, clearly the biggest technical hurdle would be in creating such massive tunnels in the first place. A hole with a ten foot radius which passed through the Earth's center would displace over twelve billion cubic feet of rock, all of which would need to be hauled away somewhere. Furthermore, the Earth's mantle and core writhe with extreme pressure and heat, so any tunnel would have to be lined with a protective shield to keep it intact.

Unfortunately no currently known materials can even withstand the hostile environment, let alone insulate the tunnel from the intense heat.

Due to these extreme temperatures, the trip may never be survivable by humans. But the technology would be extremely useful for rapid, unmanned cargo delivery between continents, essentially becoming a massive global dumbwaiter.

Those who find sport in reflecting on such wild ideas have suggested that the tunnel could be evacuated of air to eliminate wind resistance, though such a feat would prove almost as challenging as the drilling itself. Some have also postulated that such a train could be magnetically levitated to eliminate friction in situations where the tunnel does not pass through the Earth's center; though if electromagnets were used, the amount of energy consumed by the apparatus would rise drastically. A more viable location for the gravity train would be on planets such as the moon which are not troubled by an atmosphere, plate tectonics, and magma. The concept would be the same, though a planet with a density different from that of Earth would also have a different standard trip length.

Though the Gravity Express may seem impossible– or at best absurdly impractical– it is appealing to consider the possibility of extremely rapid transit across the planet with very little expenditure of energy per trip. Certainly the creation and reinforcement of such tunnels is well beyond the reach of our current technology, but the future is full of surprises.

Modern technology has sufficient momentum that it might eventually carry us through to the other side of the problem, provided that we can reduce creative friction by opening our minds.

Further reading:

• Wikipedia on the Gravity Train
• Earth sandwich

Note: This phrase has been removed from the original text: "The same principle causes a pendulum's frequency– the number of times it swings back and forth per second– to be the same regardless of how far back it is pulled before being released." This is not strictly true– my mistake.