Nanotube

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Nanotube (64)

Synopsis: Nanotech: Nanotube:

Business watch In September, French company Arkema became the latest carbon-nanotube manufacturer this year to announce plans for a drastic scaling up of production.

global nanotube production will have doubled by 2011 from around 800 tonnes per year at present. Many of these raw nanotubes are multiwalled,

because researchers were only able to experiment on mixed batches of nanotube types said Qi Zhang a graduate student in Kono's group

The Kono group's research showed plasmons rippling at terahertz frequencies only along the length of a nanotube but not across its width.

We will be making various terahertz devices architectures and systems based on carbon nanotube plasmons. Rice alumni Erik Há

or an ultimately thin nanotube he said. It could be useful for nanomechanical systems in spintronic devices as sensors as strong and light materials for mechanical applications or for energy storage.

#Waviness explains why carbon nanotube forests have low stiffnessa new study has found that waviness in forests of vertically-aligned carbon nanotubes dramatically reduces their stiffness answering a longstanding question surrounding the tiny structures.

Instead of being a detriment the waviness may make the nanotube arrays more compliant and therefore useful as thermal interface material for conducting heat away from future high-powered integrated circuits.

Measurements of nanotube stiffness which is influenced by a property known as modulus had suggested that forests of vertically-aligned nanotubes should have a much higher stiffness than

Alternately they also placed samples of the silicon-nanotube sandwiches under tensile stress--pulling them apart instead of compressing them.

whether the nanotube sandwiches were compressed or pulled apart. That suggests growth issues or buckling could not fully account for the differences observed.

They also noted that under compression the nanotubes contact one another influencing nanotube behavior. These observations were modeled mathematically to help explain what was being seen across the different conditions studied.

Now a team from Cambridge university in England has devised a simple technique to increase the density of nanotube forests grown on conductive supports about five times over previous methods.

The high density aspect is overlooked often in many carbon nanotube growth processes and is an unusual feature of our approach says John Robertson a professor in the electronic devices

The subsequent nanotube growth exhibited the highest mass density reported so far. In microelectronics this approach to growing high-density carbon nanotube forests on conductors can potentially replace

and outperform the current copper-based interconnects in a future generation of devices says Cambridge researcher Hisashi Sugime.

In the future more robust carbon nanotube forests may also help improve thermal interface materials battery electrodes and supercapacitors.

#Bismuth-carrying nanotubes show promise for CT scansscientists at Rice university have trapped bismuth in a nanotube cage to tag stem cells for X-ray tracking.

and Wilson's lab has been experimenting for years with nanotube-based contrast agents for magnetic resonance imaging (MRI) scanners.

but putting it in nanotube capsules allows us to get them inside cells in high concentrations Wilson said.

The nanotube capsules are between 20 and 80 nanometers long and about 1. 4 nanometers in diameter.

The nanotube surfaces can be modified to improve biocompatibility and their ability to target certain types of cells.

The Rice lab is working to double the amount of bismuth in each nanotube. Bismuth ions appear to get into the nanotubes by capillary action

and gadolinium into one nanotube to produce a bimodal contrast agent that can be tracked with both MRI and CT scanners.

The nanotube carpets used in the photodetectors are grown in the lab of Rice chemist Robert Hauge who pioneered a process for growing densely packed nanotubes on flat surfaces.

In the ACS Nano study lead author He used chemicals called dopants to alter the electrical properties of the nanotube carpets.

A diamond film/graphene/nanotube structure was one result of new research carried out by scientists at Rice university

when graphene is used as a middleman surfaces considered unusable as substrates for carbon nanotube growth now have the potential to do so.

Further work along these lines could produce such structures as patterned nanotube arrays on diamond that could be utilized in electronic devices Ajayan said.

The researchers think graphene facilitates nanotube growth by keeping the catalyst particles from clumping. Ajayan thinks the extreme thinness of graphene does the trick.

Testing found that the graphene layer remains intact between the nanotube forest and the diamond or other substrate.

The researchers had intended to quantify results seen a few years ago by former Rice graduate student Brent Carey who subjected a nanotube-infused polymer to a process called repetitive dynamic compression.

They had planned originally to study liquid crystal silicone/nanotube composites similar to what Carey tested but decided to look at liquid crystal silicones without the nanotubes first.

Yakobson's lab first reported in a Nano Letters paper last year that unlike graphene 2-D boron rolled into a nanotube would always be metallic.

Scientists from Rice the Dutch firm Teijin Aramid the U s. Air force and Israel's Technion Institute this week unveiled a new carbon nanotube (CNT) fiber that looks

We finally have a nanotube fiber with properties that don't exist in any other material said lead researcher Matteo Pasquali professor of chemical and biomolecular engineering and chemistry at Rice.

and colleagues to create the first pure nanotube fibers. The work established an industrially relevant wet-spinning process for nanotubes that was analogous to the methods used to create high-performance aramid fibers--like Teijin's Twaron

#Rolling neat nanotube fibers: Acid-free approach leads to strong conductive carbon threadsthe very idea of fibers made of carbon nanotubes is neat

Feeding this dense nanotube gel through a narrow needle-like opening produced continuous fiber on the Pasquali lab's equipment.

but gave the process a spin with a different preparation so now we're the first to make neat fibers of pure carbon nanotube electrolytes.

The nanotube electrolyte solution could be protected from oxygen and water which would have caused precipitation of the nanotubes he said.

or at a sharp angle simply deformed into a crumpled nanotube. But tubes that hit lengthwise actually split into ribbons with ragged edges.

Ozden explained that the even distribution of stress along the belly-flopping nanotube which is many times longer than it is wide breaks carbon bonds in a line nearly simultaneously.

#Caps not the culprit in nanotube chirality: New study narrows possibilities for gaining control of nanotube typea single-walled carbon nanotube grows from the round cap down so it's logical to think the cap's formation determines

what follows. But according to researchers at Rice university that's not entirely so. Theoretical physicist Boris Yakobson and his Rice colleagues found through exhaustive analysis that those who wish to control the chirality of nanotubes--the characteristic that determines their electrical properties--would be wise to look at other aspects of their growth.

involved in cap formation are not strong enough to dictate the nanotube's chirality. To get a clear picture of how caps are related to nanotube chirality the Rice group embarked upon a detailed two-year census of the 4500 possible cap formations for nanotubes of just two diameters 0. 8

and 1 nanometer across 21 chiralities. The cap of every nanotube has six pentagons--none

of which may touch each other--among an array of hexagons Penev said. They pull the cap

A nanotube is an atom-thick sheet of carbon atoms arranged in hexagons and rolled into a tube.

and that angle controls how well the nanotube will conduct electricity. A perfect conducting metallic nanotube would have arranged the atoms in armchairs so-called

because cutting the nanotube in half would make the top look like a series of wells with atoms for armrests.

Turn the hexagons 30 degrees though will make a semiconducting zigzag nanotube. Nanotubes can be one

or the other or the chiral angle can be anything in between with a shifting range of electrical properties.

Yakobson suspects the answer lies in tuning the interaction between the catalyst and the nanotube edge.

#Carbon nanotube fibers outperform copper in carrying electrical currenton a pound-per-pound basis carbon nanotube-based fibers invented at Rice university have greater capacity to carry electrical current

But a series of tests at Rice showed the wet-spun carbon nanotube fiber still handily beat copper carrying up to four times as much current as a copper wire of the same mass.

Scanning electron microscope images show typical carbon nanotube fibers created at Rice university and broken into two by high-current-induced Joule heating.

Kono Lab/Rice university) That said the researchers makes nanotube-based cables an ideal platform for lightweight power transmission in systems where weight is a significant factor like aerospace applications.

In the meantime the Pasquali lab has created a method to spin fiber from a mix of nanotube types that still outperforms copper.

The researchers found nanotube fibers exposed to nitrogen performed best followed by argon and open air all of

The same nanotube fibers in a vacuum could only cool by radiation and had the lowest CCC.

MIT researchers created a carbon nanotube with a bee venom-based sensor, designed to detect traces of explosives.

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