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Topic: Nanotubes


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  The stuff of dreams | CNET News.com
Single-walled nanotubes are expected to debut this year in polymers as a way to strengthen plastic parts in cars or get them to conduct electricity through normally nonconducive materials.
It comes in two basic varieties: a single-walled nanotube, which is a single coil of carbon hexagons; and a multiwalled version, wherein a single tube is encased in a wider tube, which itself is inside other tubes.
Researchers have created defect-free nanotubes as long as four microns, which is 40 times the length of the average size of features on regular silicon chips.
news.com.com /2009-7337_3-5091267.html?tag=nefd_lede   (1902 words)

  
 Carbon nanotube - Wikipedia, the free encyclopedia
Carbon nanotubes (CNTs) are an allotrope of carbon.
Nanotubes were observed in 1991 in the carbon soot of graphite electrodes during an arc discharge, by using a current of 100 amps, that was intended to produce fullerenes
Nanotubes grow at the sites of the metal catalyst; the carbon-containing gas is broken apart at the surface of the catalyst particle, and the carbon is transported to the edges of the particle, where it forms the nanotubes.
en.wikipedia.org /wiki/Nanotubes   (3662 words)

  
 Nanotubes inspire new technique for healing broken bones
Single-walled carbon nanotubes are a naturally occurring form of carbon, like graphite or diamond, where the atoms are arranged like a rolled-up tube of chicken wire.
The researchers expect that nanotubes will improve the strength and flexibility of artificial bone materials, leading to a new type of bone graft for fractures that may also be important in the treatment of bone-thinning diseases such as osteoporosis.
Simple single-walled carbon nanotubes are not sufficient, since the growth of hydroxyapatite crystals relies on the ability of the scaffold to attract calcium ions and initiate the crystallization process.
www.eurekalert.org /pub_releases/2005-07/acs-nin070705.php   (656 words)

  
 Physics News Update
Nanotubes are hot, and might be made to act like tiny filamentary light bulbs, a nanometric equivalent of the carbon filament light sources of a hundred years ago.
They are also the first to measure simultaneously the electrical resistance of the nanotube (by way of the field emissions process) and find it to obey Ohm's law.
Owing to the very tiny size of nanotubes (only nm wide) and because of this newfound control over heating, nanotubes might be ideal spot sources of heat, light, and electrons.(Purcell et al.
www.aip.org /enews/physnews/2002/split/580-2.html   (260 words)

  
 Nanotube toxicity linked to functionalization (November 2005) - News - nanotechweb.org
The results are similar to the team's findings for fullerene molecules last year, although the nanotubes were generally less toxic than the fullerenes.
"Carbon nanotubes are high-profile nanoparticles that are under consideration for dozens of applications in materials science, electronics and medical imaging," said Vicki Colvin, director of the Center for Biological and Environmental Nanotechnology (CBEN) at Rice.
Nanotubes with greater sidewall functionalization were less toxic.
nanotechweb.org /articles/news/4/11/3/1   (351 words)

  
 ScienceDaily: New Study Suggests Ways To Brighten Nanotube Light Sources   (Site not responding. Last check: 2007-10-03)
Nanotubes are the poster children of the nanotechnology revolution.
Nanotubes, which are also called buckytubes, are seamless cylinders made of carbon atoms and capped on at least one end with a buckyball hemisphere.
Nanotubes are not known to be toxic to living cells, unlike the cadmium found in quantum dots.
www.sciencedaily.com /releases/2005/11/051126142102.htm   (1998 words)

  
 Wired News: Nanotubes May Heal Broken Bones
Carbon nanotubes, incredibly strong molecules just billionths of a meter wide, can function as scaffolds for bone regrowth, according to researchers led by Robert Haddon at the University of California at Riverside.
Carbon nanotubes are an excellent choice for supporting bone, scientists say, because at the molecular scale they are the strongest human-made fiber in existence.
Though the nanotubes were treated in this case to attract a mineral that might help grow and repair bones, Strano was excited by the possibility of treating the nanotubes in other ways so that they attract, grow and direct all sorts of minerals.
www.wired.com /news/medtech/0,1286,68512,00.html   (848 words)

  
 UCSB Press Release: "'Smart' Bio-nanotubes Developed; May Help in Drug Delivery "
The nanotubes are "smart" because in the future they could be designed to encapsulate and then open up to deliver a drug or gene in a particular location in the body.
Lipid protein nanotubes made of microtuble protein (made of tubulin protein subunits shown as red-blue-yellow-green objects) that is coated by a lipid bilayer (drawn with yellow tails and green and white spherical heads) which in turn is coated by tubulin protein rings or spirals.
By controlling the relative amount of lipid and protein it is possible to switch between two states of nanotubes with either open ends (shown in the center) or closed ends with lipid caps (shown on the left), a process which forms the basis for controlled chemical and drug encapsulation and release.
www.ia.ucsb.edu /pa/display.aspx?pkey=1325   (845 words)

  
 Nanotubes
Here, we focus on our recent work on carbon nanotubes; their structure, properties and uses in nano-electronic devices.  Carbon nanotubes are extremely thin (their diameter is about 10,000 times smaller than a human hair), hollow cylinders made of carbon atoms.
  We have successfully used semiconducting single and multi-walled nanotubes as channels of field-effect transistors.
Nanotube theory: Computation and theory of the electrical and mechanical properties.
www.research.ibm.com /nanoscience/nanotubes.html   (143 words)

  
 Nanotube Research in David Tománek's Group
Recent advances in the synthesis of identical carbon nanotubes with a diameter of 1.4 nm, yet hundreds of microns in length, bear high promise for the application of these advanced materials in next-generation electronic nano-devices.
David Tománek, The growth and the death of carbon fullerenes and nanotubes.
Young-Kyun Kwon and David Tománek, Orientational melting in carbon nanotube ropes, Phys.
www.pa.msu.edu /~tomanek/nanotubes.html   (828 words)

  
 Carbon Nanotubes
Carbon nanotubes are molecular-scale tubes of graphitic carbon with outstanding properties.
These single-walled nanotubes are generally narrower than the multiwalled tubes, with diameters typically in the range 1-2 nm, and tend to be curved rather than straight.
To produce a nanotube with the indices (6,3), say, the sheet is rolled up so that the atom labelled (0,0) is superimposed on the one labelled (6,3).
www.personal.reading.ac.uk /~scsharip/tubes.htm   (1577 words)

  
 01.05.2004 - Researchers create first ever integrated silicon circuit with nanotube transistors
A carbon nanotube, which looks like rolled chicken wire when examined at the atomic level, is tens of thousands of times thinner than a human hair, yet remarkably strong.
The extreme heat required to grow nanotubes would typically melt the circuitry of traditional semiconductors, but the researchers got around that problem by interconnecting the silicon transistors with molybdenum, a refractory metal that can withstand very high temperatures.
Not only could researchers pinpoint which nanotube was responding to electrical current passing through the system, they could tell whether the conductivity could be turned on or off.
www.berkeley.edu /news/media/releases/2004/01/05_nano.shtml   (1172 words)

  
 Nanotubes Go with the Flow
The slenderness and electrical conductivity of carbon nanotubes, which resemble all-carbon rolls of chicken wire at the atomic scale, make them enticing candidates for nano-sized sensors or circuits.
The team was in the midst of experiments aimed at another problem: aligning a large group of nanotubes into a desired orientation.
Some groups have made nanotubes point the same way by gently dipping a nanotube-covered surface into water, aligning the tubes with the fluid flow, like wheat stalks blown in a wheat field.
focus.aps.org /story/v13/st7   (673 words)

  
 Nanotubes break superconducting record (February 2006) - News - PhysicsWeb   (Site not responding. Last check: 2007-10-03)
The system consists of an array of multi-walled carbon nanotubes, each of which consists of a series of concentric nanotube shells.
Next, they cut the tops off the nanotubes using ultrasound or etching techniques and then evaporated a gold electrode onto the exposed ends of the tubes.
The Japan team find that the end-bonded nanotubes lose all resistivity at temperatures below 12 K. According to the researchers, this is because the TLL states are suppressed so that superconductivity can appear.
physicsweb.org /articles/news/10/2/8/1   (415 words)

  
 Carbon Nanotube Electronics Research - Fuhrer Group
Nanotubes are very sharp, and thus can be used as probe tips for scanning-probe microscopes, and field-emission electron sources for lamps and displays.
This electrode is not in electrical contact with the nanotube, since it is separated from the nanotube by an insulator (typically silicon dioxide).
When we change the gate voltage (changing the amount of charge on the nanotube) and measure the conductance between the two contacts on the nanotube (conductance is the inverse of resistance) we see one of two types of behavior.
www.physics.umd.edu /condmat/mfuhrer/ntresearch.htm   (2619 words)

  
 Physics news Update 752
A new experiment carried out at Caltech, and reported at the AVS Science & Technology meeting in Boston, furthers the effort to employ nanotubes as a means for removing unwanted heat from microcircuits.
Carbon nanotubes, nanometer-wide cylinders made from rolled up graphitic sheets have a versatile array of mechanical, electrical, and magnetic properties.
Because phonons (the particle manifestations of heat flow) can move so freely in nanotubes, even ballistically (meaning that they refrain from scattering and travel in straight lines), the flow of heat in nanotubes should have quantum properties.
www.aip.org /pnu/2005/split/752-2.html   (206 words)

  
 WorldChanging: Tools, Models and Ideas for Building a Bright Green Future: Ribbons, Sheets and the Nanofuture
The nanotube sheets combine high transparency with high electronic conductivity, are highly flexible and provide giant gravimetric surface areas, which has enabled the team to demonstrate their use as electrodes for bright organic light emitting diodes for displays and as solar cells for light harvesting.
Since the nanotube sheets strongly absorb microwave radiation, which causes localized heating, the scientists were able to utilize a kitchen microwave oven to weld together plexiglas plates to make a window.
Neither the electrical conductivity of the nanotube sheets nor their transparency was affected by the welding process -- which suggests a novel way to imbed these sheets as transparent heating elements and antennas for car windows.
www.worldchanging.com /archives/003330.html   (4235 words)

  
 Adaptable nanotubes make way for custom-built structures, wires
Because the tiny structures flourish in the heat, the custom-built nanotubes may be especially useful in developing applications such as molecular electronics and photonics wires, or biomedical devices that could be inserted into the body, Fenniri says.
The self-assembling nanotubes are created from a series of molecules "programmed" to link in groups of six to form tiny rosette-shaped rings.
Rosette nanotubes are a new class of organic nanotubes obtained through the hierarchical self-assembly of low molecular weight synthetic modules in water (Fenniri, H. et al.
www.purdue.edu /UNS/html4ever/020311.Fenniri.scaffold.html   (1019 words)

  
 "Smoking" grass leads to nanotubes (June 2005) - News - PhysicsWeb
The nanotubes, which were about 1 micron long and 30 to 50 nanometres in diameter, could prove useful for catalyst applications (Nanotechnology 16 1192).
Many plants, including grass, contain tube-shaped bundles that are mostly made of cellulose and lignin and are used to transport fluids throughout the organism.
The tubular structure of the carbon sources appears to be crucial because using the same heat treatment on non-tubular carbohydrates, such as glucose and saccharose, produced a much lower yield of nanotubes.
physicsweb.org /articles/news/9/6/8/1   (313 words)

  
 C&EN: Latest News - DNA Nanotubes
Layers of DNA in the nanotubes are held together by hybridization of a series of DNA strands.
The DNA nanotubes are constructed in the 100-nm-diameter pores of alumina membranes.
The new DNA nanotubes could make it possible to transfer DNA without separate carriers, but this would necessitate "that these tubes are able to cross the cell membrane and reach the nucleus," which has yet to be demonstrated, Bianco notes.
pubs.acs.org /cen/news/83/i23/8323notw8.html   (454 words)

  
 ScienceDaily: Magnetic Forces May Turn Some Nanotubes Into Metals   (Site not responding. Last check: 2007-10-03)
Nanotubes, hollow cylinders of pure carbon that are just one atom thick, come in dozens of different varieties, each with a subtle difference in diameter or physical structure.
This arises from the fact that nanotubes are crystals with well-defined lattice periodicity.
Atomic-Sized Carbon Nanotubes Show Promising Tunable Structure, Electronic Properties (April 26, 2000) -- Carbon nanotubes -- strong tubular structures formed from a single layer of carbon atoms and only about a billionth of a meter in diameter -- display previously unknown properties with significant...
www.sciencedaily.com /releases/2004/05/040521073051.htm   (1983 words)

  
 Nanotubes in the Fast Lane
If engineers want to build nanoscale machines with moving parts that can generate and respond to electronic signals, those parts have got to be lightning fast.
Nanotubes form naturally in multiple concentric tubes ("multi-walled" nanotubes) with closed ends that are just nanometers in diameter.
In 2000, John Cumings and Alex Zettl of the University of California (UC) at Berkeley showed that after peeling open one end of a multiwalled tube, the inner tubes could slide in and out with very low friction [1].
focus.aps.org /story/v9/st4   (596 words)

  
 nanotubes   (Site not responding. Last check: 2007-10-03)
To build those devices, scientists must be able to manipulate the Nanotubes in a controlled way.
IBM researchers using an atomic force microscope (AFM), an instrument whose tip can apply accurately measured forces to atoms and molecules, have recently devised a means of changing a nanotube's position, shape and orientation, as well as cutting it.
IBM scientists developed a breakthrough transistor technology that could preview how computer chips can be made smaller and faster than what is currently possible with silicon.
www.research.ibm.com /topics/popups/serious/nano/html/nanotubes.html   (133 words)

  
 The presence of oxygen on carbon nanotubes enhances interaction with ammonia
Single-walled carbon nanotubes (SWNTs), which could play an important role in developing sensors against chemical threats, have enhanced interaction with ammonia because of the presence of oxygen groups on the nanotubes, researchers at Temple University have discovered.
Eric Borguet, Ph.D., associate professor of chemistry at Temple and the study's lead author, said scientists have shown that in using nanotubes for sensors, their conductivity can be changed by the presence of ammonia.
Through the use of infrared spectroscopy, Borguet and his collaborators believe they are the first to reveal that the SWNT purification process, which introduces oxygen to the nanotubes, changes the interaction with chemical species such as ammonia.
www.eurekalert.org /pub_releases/2005-07/tu-tpo071105.php   (633 words)

  
 Technology Review: Brighter Nanotubes
Carbon nanotubes are renowned for their strength, small diameter, and stunning electronic properties.
The nanotubes, which produce tightly focused light, could also be used for optical probing, manipulation, and spectroscopic analysis at the molecular level.
When nanotubes were first coaxed to produce light from electricity, she points out, the prospects seemed dim.
www.technologyreview.com /NanoTech-Materials/wtr_15925,318,p1.html   (765 words)

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