Defender_16 Posted November 29, 2005 Share Posted November 29, 2005 (edited) (It'd be great if people would post any other new advanced technology as they come out.)This particular post is on the Carbon Nanotube. This news is actually a few months old but I didn't find out about it untill a few weeks ago. Prepare for a flurry of stuff from a ton of different sources. I haven't archived the links for many (if any) of these. Carbon nanotubeFrom Wikipedia, the free encyclopedia. http://upload.wikimedia.org/wikipedia/en/thumb/4/46/Louie_nanotube.jpg/330px-Louie_nanotube.jpg Carbon nanotubes are cylindrical carbon molecules with novel properties that make them potentially useful in a wide variety of applications (e.g., nano-electronics, optics, materials applications, etc.). (Edited)http://en.wikipedia.org/wiki/Carbon_nanotube Carbon nanotube fiber & filmOne application for nanotubes that is currently being researched is high tensile strength fibers. Two methods are currently being tested for the manufacture of such fibers. A French team has developed a liquid spun system that involves pulling a fiber of nanotubes from a bath which yields a product that is approximately 60% nanotubes. The other method, which is simpler but produces weaker fibers uses traditional melt-drawn polymer fiber techniques with nanotubes mixed in the polymer. After drawing, the fibers can have the polymer burned out of them to make them purely nanotube or they can be left as they are.Ray Baughman's group from the NanoTech Institute at University of Texas at Dallas produced the current toughest material known in mid-2003 by spinning fibers of single wall carbon nanotubes with polyvinyl alcohol. Beating the previous contender, spider silk, by a factor of four, the fibers require 600 J/g to break. In comparison, the bullet-resistant fiber Kevlar is 27-33J/g. In mid-2005 Baughman and co-workers from Australia's Commonwealth Scientific and Industrial Research Organization developed a method for producing transparent carbon nanotube sheets 1/1000th the thickness of a human hair capable of supporting 50,000 times their own mass. In August 2005, Ray Baughman's team managed to develop a fast method to manufacture up to seven meters per minute of nanotube tape . Once washed with ethanol, the ribbon is only 50 nanometers thick; a square kilometer of the material would only weigh 30 kilograms.In 2004 Alan Windle's group of scientists at the Cambridge-MIT Institute developed a way to make carbon nanotube fiber continuously at the speed of several centimetres per second just as nanotubes are produced. One thread of carbon nanotubes was more than 100 metres long. The resulting fibers are electrically conductive and as strong as ordinary textile threads.   Current progressIn April of 2001, IBM announced it had developed a technique for automatically developing pure semiconductor surfaces from nanotubes. On September 19, 2003, NEC Corporation, Japan, announced stable fabrication technology of carbon nanotube transistors. High purity (80%) nanotubes were reported in June 2003 with metallic properties can be extracted with electrophoretic techniques.  As of 2003, nanotubes cost from 20 euro per gram to 1000 euro per gram, depending on purity, composition (single-wall, double-wall, multi-wall) and other characteristics. In June 2004 scientists from China's Tsinghua University and Louisiana State University demonstrated the use of nanotubes in incandescent lamps, replacing a tungsten filament in a lightbulb with a carbon nanotube one. In 2004, Nature published a photo of an individual 4 cm long single-wall nanotube (SWNT). In August 2005, GE announced the development of an ideal carbon nanotube diode that operates at the "theoretical limit," or best possible performance. The company also observed a photovoltaic effect in the nanotube diode device that could lead to breakthroughs in solar cells that make them more efficient and a more viable alternative in the mainstream energy market. In September of 2005 Texas-based Applied Nanotech, in conjunction with six Japanese electronics firms, have created a prototype of a 25-inch TV using carbon nanotubes. The prototype TV does not suffer from "ghosting," as some types of digital TVs. In September 2005 researchers at Lawrence Livermore National Laboratory demonstrated that ignition by a conventional flashbulb takes place when a layer of 29% iron enriched SWNT is placed on top of a layer of explosive material such as PETN. With ordinary explosives optical ignition is only possible with high powered lasers . In September 2005 researchers demonstrated a new way to coat MWNT's with magnetite which after orientation in a magnetic field were able to attract each other over a distance of at least 10 micrometres. . The nanotubes were functionalized with negatively charged carboxylic acid groups in a AIBN type free radical addition. Magnetite nanoparticles prepared by the Massart method were given a positive charge by washing with nitric acid which made them stick to the nanotubes by electrostatic forces. Carbon nanotubes in electrical circuitsCarbon nanotubes have many propertiesâ€”from their unique dimensions to an unusual current conduction mechanismâ€”that make them ideal components of electrical circuits. Currently, there is no reliable way to arrange carbon nanotubes into a circuit.The major hurdles that must be jumped for carbon nanotubes to find prominent places in circuits relate to fabrication difficulties. The carbon nanotube production processes are very different from the traditional IC fabrication process. The IC fabrication process is somewhat like sculptureâ€”films are deposited onto a wafer and pattern-etched away. Carbon nanotubes are fundamentally different from films; they are like atomic-level spaghetti (and every bit as sticky).Researchers sometimes resort to manipulating nanotubes one-by-one with the tip of an atomic force microscope in a painstaking, time-consuming process. Perhaps the best hope is that carbon nanotubes can be grown through a chemical vapor deposition process from patterned catalyst material on a wafer, which serve as growth sites and allow designers to position one end of the nanotube. During the deposition process, an electric field can be applied to direct the growth of the nanotubes, which tend to grow along the field lines from negative to positive polarity. Another way for the self assembly of the carbon nanotube transistors consist in using chemical or biological techniques to place the nanotubes from solution to determinate place on a substrate.Even if nanotubes could be precisely positioned, there remains the problem that, to this date, engineers have been unable to control the types of nanotubesâ€”metallic, semiconducting, single-walled, multi-walledâ€”produced. A chemical engineers solution is needed if nanotubes are to become feasible for commercial circuits. ________________________________________________________________________________________________ Purity pays off for nanotubes2 August 2005Physicists in the US have developed a new method for making electronic circuits with carbon nanotubes. The technique involves dipping semiconductor chips into a purified solution of nanotubes, rather than the conventional method of growing the nanotubes directly onto the chips. The resulting devices are much better than those produced by other approaches (Nature Materials 4 589).The features in conventional microelectronic circuits are getting smaller and smaller and will soon reach the limit imposed by the fundamental properties of silicon. Scientists hope that carbon nanotubes - which are essentially rolled up sheets of graphite, just nanometres in diameter, with excellent electronic and mechanical properties - might one day be used to replace silicon in electronic circuits. Large quantities of single-walled nanotubes can be produced by the high-pressure decomposition of carbon monoxide (HiPCO) method. However, nanotubes grown by this technique usually contain large amounts of carbon-based impurities that degrade the properties of nanotube devices. The purification method developed by Alan Johnson and colleagues at the University of Pennsylvania begins by heating nanotubes produced by the HiPCO method in wet air in the presence of hydrogen peroxide, followed by a gentle acid treatment. Next, magnetic fields are used to separate the nanotubes from the impurities. The semiconductor chips are then dipped into a solution containing the nanotubes to create circuits. "Ultimately we can make it so the nanotubes only stick where we want them to in order to form a circuit," explains lead author Danvers Johnston. The UPenn team has already made field-effect transistors from the purified nanotubes and shown that they have superior properties compared with devices made from non-purified HiPCO material. Moreover, they have shown that they can determine the energy gap of individual semiconducting nanotubes by measuring the current in their circuits and varying the temperature and gate voltage. ________________________________________________________________________________________________ Nanotube laser treatment could destroy tumours3 August 2005Researchers at the University of Stanford, US, have used single-walled carbon nanotubes and a laser to selectively destroy cancer cells. The modified nanotubes entered cancer cells and were heated by a near-infrared light beam, killing the cells.One of the longstanding problems in medicine is how to cure cancer without harming normal body tissue," said Hongjie Dai, of Stanford University. "Standard chemotherapy destroys cancer cells and normal cells alike. That's why patients often lose their hair and suffer numerous other side effects. For us, the Holy Grail would be finding a way to selectively kill cancer cells and not damage healthy ones." Dai and colleagues functionalized the nanotubes with a folate moiety. Unlike normal cells, cancer cells have receptors for folate on their surface. This means that in laboratory tests cancer cells took up the nanotubes by a process of endocytosis, but normal cells did not. Irradiating the nanotubes with near-infrared light excited electrons in the structures, causing them to heat up and destroy the surrounding cancer cells. Typically, an 808 nm-wavelength beam with a power of 1.4 W/cm2 caused extensive cell death after two minutes, but such wavelengths passed harmlessly through healthy cells. "We're using an intrinsic property of nanotubes to develop a weapon that kills cancer," said Dai. "The laser we used is a 3 cm beam that's held like a flashlight," said Dai. "We can take the beam and put it anywhere we want. We can shine it on a local area of the skin or inside an internal organ using a fibre-optic device." And that's just the start. "Folate is just an experimental model that we used," said Dai. "In reality, there are more interesting ways we can do this. For example, we can attach an antibody to a carbon nanotube to target a particular kind of cancer cell." A team from Rice University, US, has carried out a similar technique using gold nanoshells in place of carbon nanotubes. But Dai and colleagues say their nanotube method compares favourably as it needs a lower laser power and shorter radiation times to destroy cancer cells. Dai and colleagues also used nanotubes to transport molecules inside cells. They conjugated DNA to the nanotubes and allowed cells to take up the nanotubes by endocytosis. Then they used a pulsed near-infrared laser to break the membrane around the nanotube and detach the DNA. Pulsing the laser meant that it released the DNA without heating the cell sufficiently to cause its death. The result was delivery of the DNA to the cell nucleus. Dai says that delivering therapeutic molecules of DNA, RNA or protein directly into the cell nucleus could help fight various infections and diseases. The researchers reported their work in PNAS. About the authorLiz Kalaugher is editor of nanotechweb.org. UT Dallas-Led Research Team Produces Strong, Transparent Carbon Nanotube Sheets University of Texas at Dallas (UTD) nanotechnologists and an Australian colleague have produced transparent carbon nanotube sheets that are stronger than the same-weight steel sheets and have demonstrated applicability for organic light-emitting displays, low-noise electronic sensors, artificial muscles, conducting appliquÃ©s and broad-band polarized light sources that can be switched in one ten-thousandths of a second. Dr. Ray Baughman discussed this work at the 2005 nano Summit. His talk will be shown on our web site shortly. It is also discussed in the August 19 issue of Science.Carbon nanotubes are like minute bits of string, and untold trillions of these invisible strings must be assembled to make useful macroscopic articles that can exploit the phenomenal mechanical and electronic properties of the individual nanotubes. In the Aug. 19 issue of the prestigious journal Science, scientists from the NanoTech Institute at UTD and a collaborator, Dr. Ken Atkinson from Commonwealth Scientific and Industrial Research Organization (CSIRO), a national laboratory in Australia, report such assembly of nanotubes into sheets at commercially useable rates.Starting from chemically grown, self-assembled structures in which nanotubes are aligned like trees in a forest, the sheets are produced at up to seven meters per minute by the coordinated rotation of a trillion nanotubes per minute for every centimeter of sheet width. By comparison, the production rate for commercial wool spinning is 20 meters per minute. Unlike previous sheet fabrication methods using dispersions of nanotubes in liquids, which are quite slow, the dry-state process developed by the UTD-CSIRO team can use the ultra-long nanotubes needed for optimization of properties. ________________________________________________________________________________________________Nanotubes show their strength in numbersSuper-strong sheets could be used in future screens and surfacesTwo carbon nanotube sheets support droplets of orange juice, water and grape juice. The mass of each droplet is up to 50,000 times that of the contacting sheets. By Kathleen Wren Science Updated: 4:07 p.m. ET Aug. 18, 2005 WASHINGTON - Carbon nanotubes, the wunderkind molecules of the nanoworld, are finally showing strength in numbers. Researchers have now made large nanotube sheets that have many of the same star qualities as the prima donna-like single molecules, bringing the promises of nanotechnology a step closer to reality. The flexible, transparent sheets can conduct electricity and emit light or heat when a voltage is applied, leading their creators to propose that our car windows and the canopies of military aircraft could contain nearly invisible antennae, electrical heaters for defrost, or informative optical displays. These sheets, which are presently several meters long but could potentially be much larger, might also be useful in everything from flexible computer screens that could be rolled into a sack, to light bulb-like devices providing uniform lighting, to strong sails that could be propelled in space by sunlight. When you have a remarkable material, itâ€™s easy to make advances in terms of applications,â€ Edited November 30, 2005 by Defender_16 Link to comment Share on other sites More sharing options...
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