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604gq木虫 (职业作家)
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A view to the future of berkeley lab 2005-2006 report：Frontiers in Nanoscience
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Frontiers in Nanoscience Engineering a Nano Revolution It’s been said that what a society can achieve depends on what it can make. Through nanoscience, which promises the ability to build machines and create materials atom by atom, what we can make is limited only by the power of our imagination. Nanoscience is no longer the stuff of science fiction. Economists predict a trillion dollar global market for nanoproducts within the next ten years, and the Federal government is investing hundreds of millions of dollars in nanoresearch. Berkeley Lab researchers have been at the vanguard of the nano revolution; this position of leadership is about to be substantially enhanced with the addition of the Molecular Foundry.  World’s Smallest Synthetic Motor A team of scientists led by physicist Alex Zettl, who holds a joint appointment with Berkeley Lab’s Materials Sciences Division and the UC Berkeley Physics Department, succeeded in creating the world’s smallest synthetic motor. Called a synthetic rotational nanomotor, this device consisted of a gold paddle-shaped rotor blade, measuring between 100 and 300 nanometers in length, that was connected to a carbon nanotube shaft less than 10 nanometers thick. While the first version of the Berkeley nanomotor was about 300 times smaller than the diameter of a human hair, the technology behind it allows for future versions to be made even smaller — perhaps as much as five times smaller. For their accomplishment, Zettl and his colleagues received a 2004 R&D 100 Award, which is given by R&D Magazine in recognition of the “100 most technologically significant new products and advancements over the past year.” The R&D 100 Awards have been called the “Oscars of Technology.” The synthetic rotational nanomotor has been clocked at 33,000 cycles per second and is believed capable of speeds approaching one billion rotations per second. Because the carbon-carbon bonds connecting the rotor blade to the shaft are practically frictionless, the motor can run indefinitely without wearing down. It is also rugged enough to withstand the harshest of environmental conditions, including extreme temperatures and radiation. Potential applications of the synthetic rotational nanomotor technology include biological and environmental sensors, cell phones, optics, airbags, tire sensors, digital pens, blood pressure monitors, extremely smart subwoofers and antenna alignment. The technology should also find a broad range of applications in the field of cosmology for the exploration of deep space. “This was the first nanosized device where you can put external wires on it and have something rotating that you can control,” Zettl said, when the invention was announced. “There are biological motors that are slightly smaller in size, but ours can operate in a vacuum and over wide frequency and temperature ranges.” One of five nanoscience centers being established by the U.S. Department of Energy’s Office of Science, Berkeley Lab’s Molecular Foundry will provide the nanoscience community with the knowledge and tools needed to create technology that operates within the nanometer length of scale. (A nanometer is one billionth of a meter, one thousandth the size of the micrometer scale of today’s electronic technology.) It will house facilities for the development of inorganic and organic nanomaterials, nano-fabrication techniques, biological nanostructures, and nanotools. The Foundry will be adjacent to the National Center for Electron Microscopy (NCEM), which features electron microscopes capable of imaging even the tiniest features on nanosized structures. The list of advancements in nanoscience already achieved by Berkeley Lab researchers is lengthy. Scientists here were the first to grow nanocrystals in a variety of shapes, rather than the simple spheres everyone else had produced. They were the first to fashion insulated nanowires, buckyball wires sheathed in a boron nitride coating, and created the world’s first nanowire nanolasers, measuring just under 100 nanometers in diameter (about one ten-millionth of an inch). With the opening of the Molecular Foundry, Berkeley Lab researchers expect this list of accomplishments to grow.  Biologists may soon use nanotechnology to watch the inner workings of a living cell and track the effectiveness of disease-fighting drugs. These two images portray the movement of nanosized probes, called quantum dots, as they pass through a cell's membrane. In the growing world of nanosized particles, structures and devices, one of the most compelling stories has been that of quantum dots, semiconductor nanocrystals that light up like neon in a rainbow of sharp colors when bathed in ultraviolet light. Qdots, as they are known, have already fueled several startup high-tech companies, including one spun off from Berkeley Lab. Paul Alivisatos, a Berkeley Lab-UC Berkeley chemist who directs the Materials Sciences Division, is Associate Laboratory Director and one of the founders of quantum dot technology. He and his research team recently added an important new chapter to this unfolding story when they combined quantum dots with segmented nanorods to produce an extensive new array of multi-branched nanostructures. Furthermore, they learned to tune the separate components of these nanostructures and calculate the electronic interactions of their branches in three dimensions. This makes it possible to create electronic devices tailored to a variety of applications, ranging from quantum computing to artificial photosynthesis.  In another study, quantum dots were used by a Berkeley Lab and Lawrence Livermore National Laboratory team as nanosized probes for looking inside the nuclei of biological cells. The cell nucleus has been called one of the best known but least understood of all cell organelles, a knowledge gap that stems from the lack of a way to image long-term phenomena within the nuclei. Berkeley’s Fanqing Chen and Livermore’s Daniele Gerion found a way to transport silica-coated quantum dots inside cell nuclei. To slip their quantum dots past the membrane that guards entrance to the nucleus, Chen and Gerion stole a trick from the SV40 virus, which gets through the barrier with the help of a protein that binds to a cell’s nuclear trafficking mechanism. The researchers obtained a portion of this protein and attached it to their quantum dot, creating a hybrid, part biological molecule and part nanosized semiconductor, small enough to slide through the nuclear membrane’s pores, and believable enough to fool its defenses. They’ve been able to introduce and retain quantum dots in nuclei for up to a week without harming the cell. The dots fluoresce for days at sufficient resolution to detect biological events carried out by single molecules. This should allow scientists to track specific chemical reactions inside nuclei, such as how proteins help repair damaged DNA. A Lab and UC research team achieved a breakthrough by growing nanowires out of the highly prized semiconductor gallium nitride and then controling the direction in which the nanowires grew. Gallium nitride nanowires are triangular in cross section when grown on a substrate of lithium aluminum oxide but hexagonal when grown on a magnesium oxide substrate. Growth direction is critical to determining a nanowire's electrical and thermal conductivity and other important properties. In a development that brings the promise of mass production to nanoscale devices, Berkeley Lab scientists have transformed carbon nanotubes into conveyor belts capable of ferrying atom-sized particles to microscopic worksites. Someday, a nano-scale conveyor belt such as the one shown in this simulation could expedite the atom-by-atom construction of the world's smallest devices. Image courtesy of Zettl Research Group. Just as the Microtechnology Age was built upon the introduction of impurities into crystals of semiconductor materials, so too will crystalline doping be the bedrock upon which the Nanotechnology Age is built. Another Alivisatos-led team showed just what happens to nanosized crystals under the various forms of crystalline doping. They demonstrated that for nanocrystals, the doping process in which one type of positively charged atom, or cation, is exchanged for another takes place at a much faster rate than for microsized crystals, and is fully rever-sible, something that is virtually forbidden in the larger crystals under the same environmental conditions. This should accelerate the process of developing doped nanocrystals. Another breakthrough was achieved by a Berkeley Lab-UC Berkeley team led by chemist Peidong Yang, who grew nanowires out of the highly prized semiconductor gallium nitride, and controlled the direction in which these nanowires grew. Growth direction is critical to determining a nanowire’s electrical and thermal conductivity and other important properties. Nanotechnologists are eager to tap into the enormous potential of gallium nitride for use in high-power, high-performance optoelectronic devices. With further development, the technology of Yang and his colleagues should make it possible for gallium nitride nanowires to be integrated with thin films of various compositions to produce light-emitting diodes, transistors, biochemical sensors and ultraviolet-wavelength nanolasers.  Yet another development brings the promise of mass production to nanoscale devices. A team of Berkeley Lab and UC Berkeley researchers led by physicist Alex Zettl has been able to transform carbon nanotubes into conveyor belts capable of ferrying atom-sized particles to microscopic worksites. By applying a small electrical current to a carbon nanotube, the team was able to move individual atoms of indium along the tube, like auto parts on an assembly line. In a series of tests, the indium was repeatedly moved back and forth along the nanotube without losing a single atom. This research lays the groundwork for the high-throughput construction of the atomic-scale optical, electronic, and mechanical components from which future nanodevices will be fabricated. 转自: http://www.lbl.gov/Publications/annual-report/2005-2006/files/03-nanofrontiers-1.html |
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