Lengthy nanotube crop may mean super-strong fibres
17:22 27 April 2007
NewScientist.com news service
Tom Simonite




Growing lined-up nanotubes over an area several centimetres square brings them closer to mass production (Image: Vesselin Shanov/UC)



Lined-up nanotubes that are 18mm high is a new record (Vesselin Shanov/UC)


A chemical catalyst that grows carbon nanotubes to unprecedented lengths could aid efforts to make super-strong cables from the molecules.

Carbon nanotubes are incredibly strong for their size, which makes them popular with material scientists trying to toughen up existing substances or develop new ones. They have been proposed as an ideal material for making the tether for a space elevator, for example.

But growing carbon nanotubes uniformly, and making sure they are the right size and shape, is difficult. Synthesising large numbers of nanotubes longer than a few millimetres is particularly hard.

Now researchers at Cincinnati University in Ohio, US, have grown lined up nanotubes a record-breaking 18 millimetres tall. They hope that the trick for synthesising them could accelerate the development of light and super-strong cables incorporating the nanotubes.

Aligned clumps
Researchers Vasselin Shanov and Mark Schulz created aligned clumps of multi-walled nanotubes, each 18 millimetres tall and 20 nanometres wide, over an irregular area roughly 10 centimetres by 7cm.

The team presented their results at a NASA-Rice University conference on growing nanotubes in Texas, US, this month. "There's no official competition for length," Shanov says, "but all the top groups in the world were there and acknowledged we have grown the longest aligned arrays."

Researchers have previous made nanotubes that are much longer - up to 4 cm long (see Record breaker). However, these can only be produced in very low numbers and are not in alignment. The previous best for synthesising aligned nanotubes is about 14 millimetres, over an area of about 1 square centimetre.

Hot furnace
The Cincinnati team used a process called chemical vapour deposition to make their lengthy nanotubes. Acetylene or ethylene gas was pumped into a furnace heated to over 1000°C. The furnace also contained a catalyst of an undisclosed composition and structure, which was mounted on a silicon wafer. The nanotubes grew on top of this catalyst-covered surface. The catalyst is currently being patented, hence the secrecy.

Shanov says the structure of the catalyst is key. "The crucial thing is we realised that not only the catalyst but also its support is important to stop the reaction being poisoned by unwanted carbon compounds," he says. "We've made a whole new structure."

Milo Shaffer at Imperial College, London, UK, works on integrating nanotubes into composite materials to make them stronger. He says producing large numbers of long, aligned nanotubes is an attractive prospect: "In principal, they are not entangled and [should be] easier to use."

Shaffer also has little doubt the nanotubes could be used to make strong rope. "But there's a question over how long [the nanotubes] need to be," he says. "Although there is a feeling that longer would be better for fibres, it's not really been tested."

Using History To Design The Future

Visitors to Kennedy Space Center in Florida recently poured into the Saturn V Center and curiously stepped up to a display. They watched as a small group of lab-coated experts surrounded an aluminum box about the size of a file cabinet. The air filled with cautious excitement as the box was slowly unbolted and carefully lowered, exposing the contents for the first time in decades.

With an eye toward the future, the experts were working on a piece of history. NASA had commissioned the team to inspect an umbilical connection from an Apollo-era spacecraft. The agency is seeking to tap the experience of past engineers as it develops Orion, the new crew exploration vehicle for the Constellation Program.

"We're looking at this device to help improve the design for the Orion vehicle, the next-generation manned space vehicle," said Damon Delap, mechanical engineer of NASA's Glenn Research Center in Cleveland. "We're learning from the past and can see that the former engineers did it very well, so we're looking to see what they did."

NASA engineers wanted to inspect an intact Apollo-era umbilical connection, which is used to provide communication, electrical and life support connections to the astronauts in the crew compartment. They were particularly interested in the umbilical release mechanism

But finding one was like looking for a needle in a haystack because, in the Apollo days, the umbilical was severed before the astronauts came back to Earth. A guillotine-like device cut through the all the tubes and wires between the command and service modules before the crew headed home.

"The service module had all the communication and life-sustaining equipment the crew needed (in space) and, before they came back through the atmosphere, the umbilical cord had to be detached," said Dan Catalano, Orion service mechanisms and pyrotechnics lead of Glenn Research Center.

A break finally came by chance when Catalano came across a family's vacation photos posted on the Internet. There he saw the happy family standing in front of the Apollo Command Modules at the Saturn V Complex. And behind them was an umbilical housing! The Apollo spacecraft on display, designated CSM 119, was the backup for the Apollo-Soyuz Test Project but never flew. What makes this artifact so significant to the Constellation Program are the housing components located between the command and service modules.

After finding the umbilical housing -- the only one that exists intact in the United States -- NASA spent many months coordinating and planning to prepare for the inspection project. Orion Integration Engineer Tracy Gill of NASA's Kennedy, Delap, Catalano and Lamoreaux gathered at the Saturn V Center to inspect the Apollo-age capsule because of its similarity to the Orion crew compartment.

A few umbilical drawings found at the National Archives in Fort Worth, Texas, gave the engineers a "road map" to what they were seeking. "It was very worthwhile to do this and made the drawings come to life," Dunlap said.

Catalano and Dunlap worked with surgical precision to remove the housing, sometimes using only their gloved fingertips for tools. Every action was photographed, videotaped and documented. They went back and forth checking out the reference materials on a table next to the modules to be sure they were on the right track.

"Seeing the actual housing and all its contents filled in the gaps of the information we needed to take back and work on," said Catalano. "We could see the pieces that were missing in the drawings; we found them through our hands-on inspection."

The goal for the new Crew Exploration Vehicle connection is reusability. The newer design for Orion will not have the same number of tubes and wires because of today's technology, but a lot of the information that comes from this inspection will be combined with the old design that worked for the Apollo days. However, the next-generation crew module will be larger and more technologically advanced.

"It was very important to see how they built the Apollo mechanism because...well, it worked many times and instead of reinventing the wheel...it's good to start with something we know worked," said Lamoreaux. "It was a very valuable experience to come down here. I can use (the findings) to improve my design."

At the end of the inspection, the team members dexterously reassembled the housing, leaving it as they found it. They agreed that a lot will be learned from the trials, tribulations, successes and failures of the Apollo engineers, giving the "new guys" a foundation to build the new Orion vehicle even better.

When asked what it was like to have a chance to work on a piece of history, Catalano said: "For me, it's a very big highlight. I grew up in the Apollo age and used to watch all the launches. I was a product of that era. To be able to come and actually touch the hardware is a real thrill for me."

Although ownership of the Apollo Command and Service Module was transferred by NASA to the Smithsonian Institution in Washington in 1977, it is on permanent display at the Apollo/Saturn V Center at Kennedy.

Swimming dino enters the history books

2 hours, 54 minutes ago

PARIS (AFP) - Twelve footprints found in the bed of an ancient lake in northern Spain have thrown up the first compelling evidence that some land dinosaurs could swim, researchers reported Thursday.
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The 15-metre (48.75-feet) -long track in sandstone "strongly suggests a floating animal clawing the sediment" as it swam against a current, they say.

The swimmer is believed to have been a therapod -- the vast family of carnivorous dinos that included the mighty Tyrannosaurus rex -- which lived in the Early Cretaceous, some 125 million years ago.

The trackway in the former lakebed consists of six asymmetrical pairs of two or three S-shaped scratch marks. Each set measures some 50 centimetres (20 inches) in length and 15 cms (six inches) wide.

The prints paint a beguiling picture of a large, buoyant dinosaur whose clawed feet raked the sediment as it swam in a depth of some 3.2 metres (10.4 feet) of water, according to the paper, which appears in the June issue of the US journal Geology.

Ripple marks on the surface of the site indicate the dinosaur was swimming against a current, struggling to maintain a straight path.

"The dinosaur swam with alternating movements of the two hind limbs, a pelvic paddle swimming motion," said co-author Loic Costeur of the Laboratory for Planetology and Geodynamics at the University of Nantes, western France.

"It is a swimming style of amplified walking, with movements similar to those used by modern bipeds, including aquatic birds."

The question as to whether dinosaurs could swim has been debated for years.

Until now, no firm evidence had come to light, just mysterious "ghost traces" at various sites.

Asked by AFP to speculate as to which dinosaur may have made the tracks, Costeur cautiously pointed to the allosaurus -- a bipedal carnivorous dinosaur with a large skull balanced by a long, heavy tail. Some allosauruses could reach more than 10 metres (32 feet) in length.

The discovery opens up new avenues in dinosaur research, said Costeur.

Computer modelling will be able to reveal more about anatomy and biomechanics, "as well as our view of the ecological niches in which they lived."

The Virgen del Campo track is located at the Cameros Basin in La Rioja, at the site of a delta to a former lake. The basin is already known as a treasure trove of footprints of walking theropods.

Lead author is Ruben Ezquerra of the Foundation for Palaeontological Patrimony in La Rioja.

'Big Bang' project put off to 2008
POSTED: 11:18 a.m. EDT, June 6, 2007
Story Highlights
• Tests at solving the mysteries of the universe pushed back to 2008
• Scientists want to recreate conditions that existed nanoseconds after the Big Bang
• The tests involve smashing particles together at high speed
• Experiment will also probe invisible "dark matter"

GENEVA, Switzerland (Reuters) -- First tests in a scientific project aimed at solving mysteries of the universe and the "Big Bang" which created it have been put off from November to late April or early May next year, an official said on Wednesday.

James Gillies, spokesman for the CERN particle research center near Geneva, said the delay was due to a series of minor problems with some elements in the vast array of equipment.

"We now intend to make the tests, which will allow the technicians to drive the machine, in late April or early May and then to go into full start up as planned by next summer," Gillies said.

The project at CERN, the European Organization for Nuclear Research which straddles the Swiss and French border, involves smashing particles together at high speed in a channel around an oval-shaped 17 mile underground tunnel.

Researchers on the project, the Large Hadron Collider (LHC), say this will recreate in miniature the conditions which existed nanoseconds after the Big Bang some 15 billion years ago and should allow them to see what happened next.

CERN says the experiment will also probe for knowledge about "dark matter" -- the invisible mass of energy that is believed to make up 96 percent of the universe.

The LHC project, involving scientists from CERN's 26 member countries and many other nations in gathering and processing the data from many billions of particle collisions every day, has been in construction for 15 years.

It is expected to be in operation for another 15.

At the center of the experiment, which cost many billions of dollars to set up, are vast magnets in cathedral-size caverns around the tunnel some 300 feet underground.

Originally two weeks of relative low-speed testing of the circuit had been planned for November, just before CERN closes down its particle accelerators for four months to save costly energy during the winter.

But smaller magnets burst during pressure tests at the end of March, and unscheduled work resulting from that incident has meant there would not be sufficient time for the preliminary "driving" tests before the shutdown, Gillies said.