Good Vibrations: New Atom-Scale Products on Horizon
A laser in Dr. Kambhampati's lab that is used to shine light on quantum dots.
The generation of an electric field by the compression and expansion of solid materials is known as the piezoelectric effect, and it has a wide range of applications ranging from everyday items such as watches, motion sensors and precise positioning systems. Researchers at McGill University’s Department of Chemistry have now discovered how to control this effect in nanoscale semiconductors called “quantum dots,” enabling the development of incredibly tiny new products.
Although the word “quantum” is used in everyday language to connote something very large, it actually means the smallest amount by which certain physical quantities can change. A quantum dot has a diameter of only 10 to 50 atoms, or less than 10 nanometres. By comparison, the diameter of the DNA double-helix is 2 nanometres. The McGill researchers have discovered a way to make individual charges reside on the surface of the dot, which produces a large electric field within the dot. This electric field produces enormous piezoelectric forces causing large and rapid expansion and contraction of the dots within a trillionth of a second. Most importantly, the team is able to control the size of this vibration.
Cadmium Selenide quantum dots can be used in a wide range of technological applications. Solar power is one area that has been explored, but this new discovery has paved way for other nanoscale device applications for these dots. This discovery offers a way of controlling the speed and switching time of nanoelectronic devices, and possibly even developing nanoscale power supplies, whereby a small compression would produce a large voltage. (more…)
Paving Slabs that Clean the Air
Initial tests in the measuring chamber confirm that paving slabs coated with titanium dioxide can reduce ambient nitrogen oxide levels. (© Fraunhofer IME)
The concentrations of toxic nitrogen oxide that are present in German cities regularly exceed the maximum permitted levels. That’s now about to change, as innovative paving slabs that will help protect the environment are being introduced. Coated in titanium dioxide nanoparticles, they reduce the amount of nitrogen oxide in the air.
In Germany, ambient air quality is not always as good as it might be – data from the federal environment ministry makes this all too clear. In 2009, the amounts of toxic nitrogen oxide in the atmosphere exceeded the maximum permitted levels at no fewer than 55 percent of air monitoring stations in urban areas. The ministry reports that road traffi c is one of the primary sources of these emissions. In light of this fact, the Baroque city of Fulda is currently embarking on new ways to combat air pollution. Special paving slabs that will clean the air are to be laid the length of Petersberger Straße, where recorded pollution levels topped the annual mean limit of 40 micrograms per cubic meter (µg/m3) last year.
These paving slabs are coated with titanium dioxide (TiO2), which converts harmful substances such as nitrogen oxides into nitrates. Titanium dioxide is a photocatalyst; it uses sunlight to accelerate a naturallyoccurring chemical reaction, the speed of which changes with exposure to light. The “Air Clean” nitrogen oxide-reducing paving slabs were developed by F. C. Nüdling Betonelemente. Proof of their effectiveness has subsequently been provided by the Fraunhofer Institute for Molecular Biology and Applied Ecology IME in Schmallenberg, where researchers also determined the risk to the environment posed by the resulting nitrates. Their work was funded by the German Environment Foundation. (more…)
Nanotech Coatings Produce 20 Times More Electricity From Sewage
Frank Chaplen
Engineers at Oregon State University have made a significant advance toward producing electricity from sewage, by the use of new coatings on the anodes of microbial electrochemical cells that increased the electricity production about 20 times.
The findings, just published online in Biosensors and Bioelectronics, a professional journal, bring the researchers one step closer to technology that could clean biowaste at the same time it produces useful levels of electricity – a promising new innovation in wastewater treatment and renewable energy.
Engineers found that by coating graphite anodes with a nanoparticle layer of gold, the production of electricity increased 20 times. Coatings with palladium produced an increase, but not nearly as much. And the researchers believe nanoparticle coatings of iron – which would be a lot cheaper than gold – could produce electricity increases similar to that of gold, for at least some types of bacteria.
“This is an important step toward our goal,” said Frank Chaplen, an associate professor of biological and ecological engineering. “We still need some improvements in design of the cathode chamber, and a better understanding of the interaction between different microbial species. But the new approach is clearly producing more electricity.” (more…)
Researchers Cut Years from Drug Development with Nanoscopic Bead Technology
Professors Martin Guthold and Jed Macosko. (Wake Forest University photographer, Ken Bennett)
New research accepted by the Journal of Molecular Recognition confirms that a revolutionary technology developed at Wake Forest University will slash years off the time it takes to develop drugs – bringing vital new treatments to patients much more quickly.
Lab-on-Bead uses tiny beads studded with “pins” that match a drug to a disease marker in a single step, so researchers can test an infinite number of possibilities for treatments all at once. When Lab-on-Bead makes a match, it has found a viable treatment for a specific disease – speeding up drug discovery by as much as 10,000 times and cutting out years of testing and re-testing in the laboratory.
“It helps the most interesting new drugs work together to stick their heads up above the crowd,” said Jed C. Macosko, Ph.D., an associate professor of Physics at Wake Forest and primary inventor of the Lab-on-Bead technology. “Each type of drug has its own molecular barcode. Then, with the help of matching DNA barcodes on each nanoscopic bead, all the drugs of a certain type find their own ‘home’ bead and work together to make themselves known in our drug discovery process. It’s kind of like when Dr. Seuss’s Whos down in Whoville all yelled together so that Horton the elephant and all of his friends could hear them.” (more…)
Researchers Create Self-Assembling Nanodevices that Move and Change Shape on Demand
Donald Ingber, M.D., Ph.D., founding director of the Wyss Institute for Biologically Inspired Engineering at Harvard University.
By emulating nature’s design principles, a team at Harvard’s Wyss Institute for Biologically Inspired Engineering, Harvard Medical School and Dana-Farber Cancer Institute has created nanodevices made of DNA that self-assemble and can be programmed to move and change shape on demand. In contrast to existing nanotechnologies, these programmable nanodevices are highly suitable for medical applications because DNA is both biocompatible and biodegradable.
The work appears in the June 20 advance online Nature Nanotechnology.
Built at the scale of one billionth of a meter, each device is made of a circular, single-stranded DNA molecule that, once it has been mixed together with many short pieces of complementary DNA, self-assembles into a predetermined 3D structure. Double helices fold up into larger, rigid linear struts that connect by intervening single-stranded DNA. These single strands of DNA pull the struts up into a 3D form—much like tethers pull tent poles up to form a tent. The structure’s strength and stability result from the way it distributes and balances the counteracting forces of tension and compression.
This architectural principle—known as tensegrity—has been the focus of artists and architects for many years, but it also exists throughout nature. In the human body, for example, bones serve as compression struts, with muscles, tendons and ligaments acting as tension bearers that enable us to stand up against gravity. The same principle governs how cells control their shape at the microscale. (more…)
Scientists Strive to Replace Silicon with Graphene on Nanocircuitry
In a technique known as thermochemical nanolithography, the tip of an atomic force microscope uses heat to turn graphene oxide into reduced graphene oxide, a substance that can be used to produce nanocircuits and nanowires with controllable conductivity. (University of Illinois at Urbana-Champaign)
Scientists have made a breakthrough toward creating nanocircuitry on graphene, widely regarded as the most promising candidate to replace silicon as the building block of transistors. They have devised a simple and quick one-step process based on thermochemical nanolithography (TCNL) for creating nanowires, tuning the electronic properties of reduced graphene oxide on the nanoscale and thereby allowing it to switch from being an insulating material to a conducting material.
The technique works with multiple forms of graphene and is poised to become an important finding for the development of graphene electronics. The research appears in the June 11, 2010, issue of the journal Science.
Scientists who work with nanocircuits are enthusiastic about graphene because electrons meet with less resistance when they travel along graphene compared to silicon and because today’s silicon transistors are nearly as small as allowed by the laws of physics. Graphene also has the edge due to its thickness - it’s a carbon sheet that is a single atom thick. While graphene nanoelectronics could be faster and consume less power than silicon, no one knew how to produce graphene nanostructures on such a reproducible or scalable method. That is until now.
“We’ve shown that by locally heating insulating graphene oxide, both the flakes and epitaxial varieties, with an atomic force microscope tip, we can write nanowires with dimensions down to 12 nanometers. And we can tune their electronic properties to be up to four orders of magnitude more conductive. We’ve seen no sign of tip wear or sample tearing,” said Elisa Riedo, associate professor in the School of Physics at the Georgia Institute of Technology. (more…)
New Nanoscale Electrical Phenomenon Discovered
A University of Michigan biomedical engineering professor Alan Hunt.
At the scale of the very small, physics can get peculiar. A University of Michigan biomedical engineering professor has discovered a new instance of such a nanoscale phenomenon—one that could lead to faster, less expensive portable diagnostic devices and push back frontiers in building micro-mechanical and “lab on a chip” devices.
In our macroscale world, materials called conductors effectively transmit electricity and materials called insulators or dielectrics don’t, unless they are jolted with an extremely high voltage. Under such “dielectric breakdown” circumstances, as when a bolt of lightening hits a rooftop, the dielectric (the rooftop in this example) suffers irreversible damage.
This isn’t the case at the nanoscale, according to a new discovery by Alan Hunt, an associate professor in the Department of Biomedical Engineering. Hunt and his research team were able to get an electric current to pass nondestructively through a sliver of glass, which isn’t usually a conductor.
A paper on the research is newly published online in Nature Nanotechnology.
“This is a new, truly nanoscale physical phenomenon,” Hunt said. “At larger scales, it doesn’t work. You get extreme heating and damage. (more…)
The Rise of the Molecular Robots
Researchers have created and observed a molecular robot capable of many steps, and of making decisions where to step and how long to stay. As the robot walks on the substrate, it changes each piece by cleaving off a part. If it touches a spot that has been cleaved already, it does not linger as long. The end of the track glows red and captures the robot, letting the researchers know when it has completed its walk. The robot glows green, allowing for the researchers to see it better. (Credit: Zina Deretsky, National Science Foundation)
Researchers from Columbia University, Arizona State University, the University of Michigan and the California Institute of Technology (Caltech) have created and programmed robots the size of single molecule that can move independently across a nano-scale track. This development, outlined in the May 13 edition of the journal Nature, marks an important advancement in the nascent fields of molecular computing and robotics, and could someday lead to molecular robots that can fix individual cells or assemble nanotechnology products.
The project was led by Milan N. Stojanovic, a faculty member in the division of experimental therapeutics at Columbia University, who partnered with Erik Winfree, associate professor of computer science at Caltech, Hao Yan, professor of chemistry and biochemistry at Arizona State University and an expert in DNA nanotechnology, and with Nils G. Walter, professor of chemistry and director of the Single Molecule Analysis in Real-Time (SMART) Center at the University of Michigan in Ann Arbor. Their work was supported in part by the National Science Foundation.
The word ‘robot’ makes most people think of solid machines that use computer circuitry to perform defined jobs, such as vacuuming a carpet or welding together automobiles. In recent years, scientists have worked to create robots that could also reliably perform useful tasks, but at a molecular level. This is, needless to say, not a simple endeavor, and it involves reprogramming DNA molecules to perform in specific ways. “Can you instruct a biomolecule to move and function in a certain way–researchers at the interface of computer science, chemistry, biology and engineering are attempting to do just that,” says Mitra Basu, a program director at NSF responsible for the agency’s support to this research. (more…)
Survey: Hiding Risks Can Hurt Public Support For Nanotechnology
This illustration was used to represent a nanoscale medical device in the national survey on public attitudes towards the use of nanotechnology for human enhancement.
A new national survey on public attitudes toward medical applications and physical enhancements that rely on nanotechnology shows that support for the technology increases when the public is informed of the technology’s risks as well as its benefits – at least among those people who have heard of nanotechnology. The survey, which was conducted by researchers at North Carolina State University and Arizona State University (ASU), also found that discussing risks decreased support among those people who had never previously heard of nanotechnology – but not by much.
“The survey suggests that researchers, industries and policymakers should not be afraid to display the risks as well as the benefits of nanotechnology,” says Dr. Michael Cobb, an associate professor of political science at NC State who conducted the survey. “We found that when people know something about nanotechnologies for human enhancement, they are more supportive of it when they are presented with balanced information about its risks and benefits.”
This illustration was used to represent a nanoscale medical device in the national survey on public attitudes towards the use of nanotechnology for human enhancement. (more…)
Viruses Harnessed to Create Hydrogen Fuel from Water
Angela Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering, demonstrates a virus-templated catalyst solution used in harnessing energy from water. Photo: Dominick Reuter
A team of MIT researchers has found a novel way to mimic the process by which plants use the power of sunlight to split water and make chemical fuel to power their growth. In this case, the team used a modified virus as a kind of biological scaffold that can assemble the nanoscale components needed to split a water molecule into hydrogen and oxygen atoms.
Splitting water is one way to solve the basic problem of solar energy: It’s only available when the sun shines. By using sunlight to make hydrogen from water, the hydrogen can then be stored and used at any time to generate electricity using a fuel cell, or to make liquid fuels (or be used directly) for cars and trucks.
Other researchers have made systems that use electricity, which can be provided by solar panels, to split water molecules, but the new biologically based system skips the intermediate steps and uses sunlight to power the reaction directly. The advance is described in a paper published on April 11 in Nature Nanotechnology.
The team, led by Angela Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering, engineered a common, harmless bacterial virus called M13 so that it would attract and bind with molecules of a catalyst (the team used iridium oxide) and a biological pigment (zinc porphyrins). The viruses became wire-like devices that could very efficiently split the oxygen from water molecules.
Over time, however, the virus-wires would clump together and lose their effectiveness, so the researchers added an extra step: encapsulating them in a microgel matrix, so they maintained their uniform arrangement and kept their stability and efficiency. (more…)
Creating Atomic-Scale ‘Black Holes’
Launched laser-cooled atoms are captured by a single, suspended, single-wall carbon nanotube charged to hundreds of volts. A captured atom spirals towards the nanotube (white path) and reaches the environs of the tube surface, where its valence electron (yellow) tunnels into the tube. The resulting ion (purple) is ejected and detected, and the dynamics at the nanoscale are sensitively probed. (Anne Goodsell and Tommi Hakala/Harvard University)
Carbon nanotubes, long touted for applications in materials and electronics, may also be the stuff of atomic-scale black holes.
Physicists at Harvard University have found that a high-voltage nanotube can cause cold atoms to spiral inward under dramatic acceleration before disintegrating violently. Their experiments, the first to demonstrate something akin to a black hole at atomic scale, are described in the current issue of the journal Physical Review Letters.
“On a scale of nanometers, we create an inexorable and destructive pull similar to what black holes exert on matter at cosmic scales,” says Lene Vestergaard Hau, Mallinckrodt Professor of Physics and of Applied Physics at Harvard. “As importantly for scientists, this is the first merging of cold-atom and nanoscale science, and it opens the door to a new generation of cold atom experiments and nanoscale devices.”
Hau and co-authors Anne Goodsell, Trygve Ristroph, and Jene A. Golovchenko laser-cooled clouds of one million rubidium atoms to just a fraction of a degree above absolute zero. The physicists then launched this millimeter-long atomic cloud towards a suspended carbon nanotube, located some two centimeters away and charged to hundreds of volts. (more…)
New Tools for Nanoscience
Nanoscience researchers at Cornell University. (Courtesy: KIC/Cornell)
Directors of the Kavli Institute at Cornell for Nanoscale Science, Paul McEuen and David A. Muller, talk about their mission to push the technology of observation, measurement and control to ever-smaller dimensions.
In nanoscience, researchers are truly limited by the technology of their field, needing increasingly more advanced tools for studying, analyzing and manipulating objects and systems at the scale of individual molecules and atoms.
To expand the boundaries of nanoscience, the Kavli Institute at Cornell for Nanoscale Science is now devoted to the development and utilization of next-generation tools for exploring the nanoscale world. The new director of the institute is Cornell University Physics Professor Paul McEuen, widely known for his work with carbon-based systems such as graphene and nanotubes. Serving as co-director is Associate Professor of Applied and Engineering Physics David A. Muller, whose pioneering work includes developing electron energy loss spectroscopy as a tool for predicting materials properties.
Recently, McEuen and Muller discussed the institute’s new mission and the need for advanced technology in nanoscience. In particularly, they described how they had come upon limits of observation and control in their own work, and how they plan to launch “high-risk, high-payoff” projects with the potential of changing the way scientists work worldwide. In McEuen’s words, “we’re looking for projects where you could say, ‘If I succeed, suddenly everybody’s going to want one of these.’” (more…)
Scientists Discover World’s Smallest Superconductor
This image shows the smallest superconductor, which is only .87 nanometer wide. (Image courtesy of Saw-Wai Hla and Kendal Clark, Ohio University)
Scientists have discovered the world’s smallest superconductor, a sheet of four pairs of molecules less than one nanometer wide. The Ohio University-led study, published today as an advance online publication in the journal Nature Nanotechnology, provides the first evidence that nanoscale molecular superconducting wires can be fabricated, which could be used for nanoscale electronic devices and energy applications.
“Researchers have said that it’s almost impossible to make nanoscale interconnects using metallic conductors because the resistance increases as the size of wire becomes smaller. The nanowires become so hot that they can melt and destruct. That issue, Joule heating, has been a major barrier for making nanoscale devices a reality,” said lead author Saw-Wai Hla, an associate professor of physics and astronomy with Ohio University’s Nanoscale and Quantum Phenomena Institute.
Superconducting materials have an electrical resistance of zero, and so can carry large electrical currents without power dissipation or heat generation. Superconductivity was first discovered in 1911, and until recently, was considered a macroscopic phenomenon. The current finding suggests, however, that it exists at the molecular scale, which opens up a novel route for studying this phenomenon, Hla said. Superconductors currently are used in applications ranging from supercomputers to brain imaging devices. (more…)
Researchers Discover New Way of Producing Electricity
By David L. Chandler
A carbon nanotube (shown in illustration) can produce a very rapid wave of power when it is coated by a layer of fuel and ignited, so that heat travels along the tube. (Graphic: Christine Daniloff)
A team of scientists at MIT have discovered a previously unknown phenomenon that can cause powerful waves of energy to shoot through minuscule wires known as carbon nanotubes. The discovery could lead to a new way of producing electricity, the researchers say.
The phenomenon, described as thermopower waves, “opens up a new area of energy research, which is rare,” says Michael Strano, MIT’s Charles and Hilda Roddey Associate Professor of Chemical Engineering, who was the senior author of a paper describing the new findings that appeared in Nature Materials on March 7. The lead author was Wonjoon Choi, a doctoral student in mechanical engineering.
Like a collection of flotsam propelled along the surface by waves traveling across the ocean, it turns out that a thermal wave — a moving pulse of heat — traveling along a microscopic wire can drive electrons along, creating an electrical current.
The key ingredient in the recipe is carbon nanotubes — submicroscopic hollow tubes made of a chicken-wire-like lattice of carbon atoms. These tubes, just a few billionths of a meter (nanometers) in diameter, are part of a family of novel carbon molecules, including buckyballs and graphene sheets, that have been the subject of intensive worldwide research over the last two decades. (more…)
Chemist Monitors Nanotechnology’s Environmental Impact
Omowunmi Sadik, director of Binghamton University’s Center for Advanced Sensors and Environmental Systems, is developing sensors that would detect and identify engineered nanoparticles. (Jonathan Cohen/Binghamton University)
Interest in ‘green’ innovation means not just thinking big but also very, very, very small.
At least that’s the way Omowunmi Sadik, director of Binghamton University’s Center for Advanced Sensors and Environmental Systems, sees it. She’s working to develop sensors that would detect and identify engineered nanoparticles. Her research will advance our understanding of the risks associated with the environmental release and transformation of these particles.
“Society has a duty to not only consider the positive sides of science and technology but also the not-so-desirable sides of technology itself,” said Sadik, a professor of chemistry. “We need to think not just about how to make these nanoparticles but also about their impact on human health and the environment.”
A survey by the Project on Emerging Nanotechnologies found that nanoparticles — particles less than 100 nanometers in size — are now used in more than 1,000 consumer products ranging from cars to food. Silver nanoparticles are widely used as coating materials in cookware and tableware and as ingredients in laundry liquids and clothes because of their antibacterial properties. You can even buy socks infused with silver nanoparticles designed to reduce bacteria and odor.
“But what happens if we buy those socks and we wash them?” Sadik asked. “The nanoparticles end up in our water system.” (more…)
Engineers: Weak Laser Can Ignite Nanoparticles, With Exciting Possibilities
By Aaron Hoover
University of Florida engineering researchers have found they can ignite certain nanoparticles using a low-power laser, a development they say opens the door to a wave of new technologies in health care, computing and automotive design.
A paper about the research appears in this week’s advance online edition of Nature Nanotechnology.
Vijay Krishna, Nathanael Stevens, Ben Koopman and Brij Moudgil say they used lasers not much more intense than those found in laser pointers to light up, heat or ignite manufactured carbon molecules, known as fullerenes, whose soccer-ball-like shapes had been distorted in certain ways. They said the discovery suggests a score of important new applications for these so-called “functionalized fullerenes” molecules already being developed for a broad range of industries and commercial and medical products.
“The beauty of this is that it only requires a very low intensity laser,” said Moudgil, professor of materials science and engineering and director of the engineering college’s Particle Engineering Research Center, where the research was conducted. (more…)
Like Little Golden Assassins, ‘Smart’ Nanoparticles Identify, Target and Kill Cancer Cells
Project director Carl Batt, left, is the Liberty Hyde Bailey Professor in Cornell's Department of Food Science. (Richard Killen/University Photography)
Another weapon in the arsenal against cancer: Nanoparticles that identify, target and kill specific cancer cells while leaving healthy cells alone.
Led by Carl Batt, the Liberty Hyde Bailey Professor of Food Science, the researchers synthesized nanoparticles – shaped something like a dumbbell – made of gold sandwiched between two pieces of iron oxide. They then attached antibodies, which target a molecule found only in colorectal cancer cells, to the particles. Once bound, the nanoparticles are engulfed by the cancer cells.
To kill the cells, the researchers use a near-infrared laser, which is a wavelength that doesn’t harm normal tissue at the levels used, but the radiation is absorbed by the gold in the nanoparticles. This causes the cancer cells to heat up and die.
“This is a so-called ‘smart’ therapy,” Batt said. “To be a smart therapy, it should be targeted, and it should have some ability to be activated only when it’s there and then kills just the cancer cells.”
The goal, said lead author and biomedical graduate student Dickson Kirui, is to improve the technology and make it suitable for testing in a human clinical trial. The researchers are now working on a similar experiment targeting prostate cancer cells. (more…)
Vigilance Needed in Nanotechnology
David Cramb
University of Calgary chemistry professor David Cramb is a step closer to helping solve a complex problem in nanotechnology: the impact nanoparticles have on human health and the environment.
Cramb, director of the Faculty of Science’s nanoscience program, and his researchers have developed a methodology to measure various aspects of nanoparticles in the blood stream of chicken embryos. Their discovery is published in the March online edition of Chemical Physics Letters.
“With the boom in nanomaterials production there is an increasing possibility of environmental and/or human exposure. Thus there is a need to investigate their potential detrimental effects,” says Cramb. “We have developed very specialized tools to begin measuring such impacts.”
Nanoparticles are particles or groups of atoms or molecules nanometers in size. One millimetre (or the diameter of the head of a pin) is equal to one-million nanometres. Nanoparticles are already used in the cosmetics industry and are being developed for drug delivery, diagnostic imaging and tissue engineering, to name only a few applications. It is estimated investments in nanotechnology globally will reach about $12 trillion US by 2012.
Cramb is looking for ways to help answer questions including: If embryos are exposed to nanoparticles, where will the nanoparticles go? How will the embryo respond? What regulatory approaches can be recommended to mitigate accidental exposure? How can nanotechnology be made green and sustainable? (more…)
Physicists Build Basic Quantum Computing Circuit
W-Madison physics professor Mark Saffman.
Exerting delicate control over a pair of atoms within a mere seven-millionths-of-a-second window of opportunity, physicists at the University of Wisconsin-Madison created an atomic circuit that may help quantum computing become a reality.
Quantum computing represents a new paradigm in information processing that may complement classical computers. Much of the dizzying rate of increase in traditional computing power has come as transistors shrink and pack more tightly onto chips — a trend that cannot continue indefinitely.
“At some point in time you get to the limit where a single transistor that makes up an electronic circuit is one atom, and then you can no longer predict how the transistor will work with classical methods,” explains UW-Madison physics professor Mark Saffman. “You have to use the physics that describes atoms — quantum mechanics.”
At that point, he says, “you open up completely new possibilities for processing information. There are certain calculational problems… that can be solved exponentially faster on a quantum computer than on any foreseeable classical computer.”
With fellow physics professor Thad Walker, Saffman successfully used neutral atoms to create what is known as a controlled-NOT (CNOT) gate, a basic type of circuit that will be an essential element of any quantum computer. As described in the Jan. 8 issue of the journal Physical Review Letters, the work is the first demonstration of a quantum gate between two uncharged atoms. (more…)
Accidental Discovery Leads to Nano Revelation
Two gold nanowires weld when their tips touch. (Jun Lou/Rice University)
Welding uses heat to join pieces of metal in everything from circuits to skyscrapers. But Rice University researchers have found a way to beat the heat on the nanoscale.
Jun Lou, an assistant professor in mechanical engineering and materials science, and his group have discovered that gold wires between three-billionths and 10-billionths of a meter wide weld themselves together quite nicely – without heat.
They report in today’s online edition of the journal Nature Nanotechnology that clean gold nanowires with identical atomic structures will merge into a single wire that loses none of its electrical and mechanical properties. The process works just as well with silver nanowires, which bond with each other or with gold.
This cold-welding process has been observed on the macro scale for decades, Lou said. Clean, flat pieces of similar metals can be made to bond under high pressure and in a vacuum. But only Lou and his colleagues have seen the process happen on the nanoscale, under an electron microscope.
As so often happens in basic research, that’s not what they were looking for at all. Lou and Rice graduate student Yang Lu, with collaborators at Sandia National Laboratories and Brown University, were trying to determine the tensile strength of gold nanowires by attaching one end of a wire to a probe in a transmission electron microscope (TEM) and the other to a tiny cantilever spring called an atomic force microscopy (AFM) probe. (more…)
New Fiber Nanogenerators Could Lead to Electric Clothing
By Sarah Yang
Shown is a fiber nanogenerator on a plastic substrate created by UC Berkeley scientists. The nanofibers can convert energy from mechanical stresses and into electricity, and could one day be used to create clothing that can power small electronics. (Chieh Chang, UC Berkeley)
In research that gives literal meaning to the term “power suit,” University of California, Berkeley, engineers have created energy-scavenging nanofibers that could one day be woven into clothing and textiles.
These nano-sized generators have “piezoelectric” properties that allow them to convert into electricity the energy created through mechanical stress, stretches and twists.
“This technology could eventually lead to wearable ’smart clothes’ that can power hand-held electronics through ordinary body movements,” said Liwei Lin, UC Berkeley professor of mechanical engineering and head of the international research team that developed the fiber nanogenerators.
Because the nanofibers are made from organic polyvinylidene fluoride, or PVDF, they are flexible and relatively easy and cheap to manufacture.
Although they are still working out the exact calculations, the researchers noted that more vigorous movements, such as the kind one would create while dancing the electric boogaloo, should theoretically generate more power. “And because the nanofibers are so small, we could weave them right into clothes with no perceptible change in comfort for the user,” said Lin, who is also co-director of the Berkeley Sensor and Actuator Center at UC Berkeley. (more…)
Engineers Explore Environmental Concerns of Nanotechnology
Peter Vikesland and Linsey Marr, both associate professors of civil and environmental engineering at Virginia Tech, are members of the national Center for the Environmental Implications of NanoTechnology (CEINT) at Virginia Tech. They are exploring the impact of nanotechnology research on the environment. (Virginia Tech Photo)
As researchers around the world hasten to employ nanotechnology to improve production methods for applications that range from manufacturing materials to creating new pharmaceutical drugs, a separate but equally compelling challenge exists.
History has shown that previous industrial revolutions, such as those involving asbestos and chloroflurocarbons, have had some serious environmental impacts. Might nanotechnology also pose a risk?
Linsey Marr and Peter Vikesland, faculty members in the Via Department of Civil and Environmental Engineering at Virginia Tech, are part of the national Center for the Environmental Implications of NanoTechnology (CEINT), funded by the National Science Foundation (NSF) in 2008. Along with Michael Hochella, University Distinguished Professor of Geosciences, they represent Virginia Tech’s efforts in a nine-member consortium awarded $14 million over five years, starting in 2008. Virginia Tech’s portion is $1.75 million.
CEINT is dedicated to elucidating the relationship between a vast array of nanomaterials — from natural, to manufactured, to those produced incidentally by human activities — and their potential environmental exposure, biological effects, and ecological consequences. It will focus on the fate and transport of natural and manufactured nanomaterials in ecosystems. (more…)
‘Nanodragster’ Races Toward the Future of Molecular Machines
The new "nanodragster" (left) may lead to molecular machines for manufacturing computer circuits and other electronic components. (American Chemical Society)
Scientists in Texas are reporting the development of a “nanodragster” that may speed the course toward development of a new generation of futuristic molecular machines. The vehicle — only 1/50,000th the width of a human hair — resembles a hot-rod in shape and can outperform previous nano-sized vehicles. Their report is in ACS’ Organic Letters, a bi-weekly journal.
James Tour, Kevin Kelly and colleagues note that the ability to control the motion of small molecules is essential for building much-anticipated molecular machines. Some of these machines may find use in manufacturing computer circuits and other electronic components in the future. Scientists have already made strides by designing nano-sized vehicles, including a “nanocar” with wheels made of buckyballs — spheres of carbon containing 60 atoms apiece. The car can scoot around a gold surface when exposed to heat or an electric field gradient. But control of its movement is limited. These drawbacks prevent its widespread use. But the most limiting factor is the nanoscopic resolution tools available for studying their range of motions and capabilities. (more…)
Nanoparticle Protects Oil in Foods from Oxidation, Spoilage
by Brian Wallheimer
Using a nanoparticle from corn, a Purdue University scientist has found a way to lengthen the shelf life of many food products and sustain their health benefits.
Yuan Yao, an assistant professor of food science, has successfully modified the phytoglycogen nanoparticle, a starchlike substance that makes up nearly 30 percent of the dry mass of some sweet corn. The modification allows the nanoparticle to attach to oils and emulsify them while also acting as a barrier to oxidation, which causes food to become rancid. His findings were published in the early online version of the Journal of Agricultural and Food Chemistry.
Oxidation destabilizes oil droplets in emulsified food, degrading and changing the chemical structure of the oil and causing it to go bad. This oxidation happens in a wide range of products, shortening their shelf lives.
“This can be widely used in the food industry, cosmetics and nutritional supplements, any system in which the oxidation of lipids is a concern,” Yao said. “The shelf life of a product can be low and the quality of the food can become bad because of the oxidation of the lipids.”
In fish oils, for example, the lipid oxidation degrades Omega-3 fatty acids, which are essential in infant development and are thought to help with chronic inflammatory and heart diseases in adults. (more…)
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